Collaboration diagram for Bucket Brigades:

Classes
struct	apr_bucket_type_t
struct	apr_bucket
struct	apr_bucket_brigade
struct	apr_bucket_refcount
struct	apr_bucket_heap
struct	apr_bucket_pool
struct	apr_bucket_file
union	apr_bucket_structs
Defines
#define	APR_BUCKET_BUFF_SIZE 8000
#define	APR_BRIGADE_CHECK_CONSISTENCY(b)
#define	APR_BUCKET_CHECK_CONSISTENCY(e)
#define	APR_BRIGADE_SENTINEL(b) APR_RING_SENTINEL(&(b)->list, apr_bucket, link)
#define	APR_BRIGADE_EMPTY(b) APR_RING_EMPTY(&(b)->list, apr_bucket, link)
#define	APR_BRIGADE_FIRST(b) APR_RING_FIRST(&(b)->list)
#define	APR_BRIGADE_LAST(b) APR_RING_LAST(&(b)->list)
#define	APR_BRIGADE_INSERT_HEAD(b, e)
#define	APR_BRIGADE_INSERT_TAIL(b, e)
#define	APR_BRIGADE_CONCAT(a, b)
#define	APR_BRIGADE_PREPEND(a, b)
#define	APR_BUCKET_INSERT_BEFORE(a, b)
#define	APR_BUCKET_INSERT_AFTER(a, b)
#define	APR_BUCKET_NEXT(e) APR_RING_NEXT((e), link)
#define	APR_BUCKET_PREV(e) APR_RING_PREV((e), link)
#define	APR_BUCKET_REMOVE(e) APR_RING_REMOVE((e), link)
#define	APR_BUCKET_INIT(e) APR_RING_ELEM_INIT((e), link)
#define	APR_BUCKET_IS_METADATA(e) ((e)->type->is_metadata)
#define	APR_BUCKET_IS_FLUSH(e) ((e)->type == &apr_bucket_type_flush)
#define	APR_BUCKET_IS_EOS(e) ((e)->type == &apr_bucket_type_eos)
#define	APR_BUCKET_IS_FILE(e) ((e)->type == &apr_bucket_type_file)
#define	APR_BUCKET_IS_PIPE(e) ((e)->type == &apr_bucket_type_pipe)
#define	APR_BUCKET_IS_SOCKET(e) ((e)->type == &apr_bucket_type_socket)
#define	APR_BUCKET_IS_HEAP(e) ((e)->type == &apr_bucket_type_heap)
#define	APR_BUCKET_IS_TRANSIENT(e) ((e)->type == &apr_bucket_type_transient)
#define	APR_BUCKET_IS_IMMORTAL(e) ((e)->type == &apr_bucket_type_immortal)
#define	APR_BUCKET_IS_POOL(e) ((e)->type == &apr_bucket_type_pool)
#define	APR_BUCKET_ALLOC_SIZE APR_ALIGN_DEFAULT(2*sizeof(apr_bucket_structs))
#define	apr_bucket_destroy(e)
#define	apr_bucket_delete(e)
#define	apr_bucket_read(e, str, len, block) (e)->type->read(e, str, len, block)
#define	apr_bucket_setaside(e, p) (e)->type->setaside(e,p)
#define	apr_bucket_split(e, point) (e)->type->split(e, point)
#define	apr_bucket_copy(e, c) (e)->type->copy(e, c)
Typedefs
typedef struct apr_bucket_brigade	apr_bucket_brigade
typedef struct apr_bucket	apr_bucket
typedef struct apr_bucket_alloc_t	apr_bucket_alloc_t
typedef struct apr_bucket_type_t	apr_bucket_type_t
typedef apr_status_t(*	apr_brigade_flush )(apr_bucket_brigade bb, void ctx)
typedef struct apr_bucket_refcount	apr_bucket_refcount
typedef struct apr_bucket_heap	apr_bucket_heap
typedef struct apr_bucket_pool	apr_bucket_pool
typedef struct apr_bucket_file	apr_bucket_file
typedef union apr_bucket_structs	apr_bucket_structs
Enumerations
enum	apr_read_type_e { APR_BLOCK_READ, APR_NONBLOCK_READ }
Functions
	APU_DECLARE (apr_bucket_brigade ) apr_brigade_create(apr_pool_t p
	APU_DECLARE (apr_status_t) apr_brigade_destroy(apr_bucket_brigade *b)
	APU_DECLARE_NONSTD (apr_status_t) apr_brigade_putstrs(apr_bucket_brigade *b
apr_brigade_flush void apr_brigade_flush void const char	__attribute__ ((format(printf, 4, 5)))
	APU_DECLARE (apr_bucket ) apr_brigade_insert_file(apr_bucket_brigade bb
	APU_DECLARE_NONSTD (apr_bucket_alloc_t ) apr_bucket_alloc_create(apr_pool_t p)
	APU_DECLARE_NONSTD (void) apr_bucket_alloc_destroy(apr_bucket_alloc_t *list)
	APU_DECLARE_NONSTD (void *) apr_bucket_alloc(apr_size_t size
Variables
apr_bucket_alloc_t *	list
apr_bucket *	e
apr_bucket apr_bucket_brigade *	a
apr_off_t	point
apr_off_t apr_bucket **	after_point
int	read_all
int apr_off_t *	length
char *	c
char apr_size_t *	len
char apr_size_t apr_pool_t *	pool
apr_bucket_brigade *	bbIn
apr_bucket_brigade apr_read_type_e	block
apr_bucket_brigade apr_read_type_e apr_off_t	maxbytes
struct iovec *	vec
struct iovec int *	nvec
apr_brigade_flush	flush
apr_brigade_flush void *	ctx
apr_brigade_flush void va_list	va
apr_brigade_flush void const char *	str
apr_brigade_flush void const char apr_size_t	nbyte
apr_brigade_flush void apr_brigade_flush void const char *	fmt
apr_file_t *	f
apr_file_t apr_off_t	start
apr_file_t apr_off_t apr_off_t apr_pool_t *	p
APU_DECLARE_DATA const apr_bucket_type_t	apr_bucket_type_flush
APU_DECLARE_DATA const apr_bucket_type_t	apr_bucket_type_eos
APU_DECLARE_DATA const apr_bucket_type_t	apr_bucket_type_file
APU_DECLARE_DATA const apr_bucket_type_t	apr_bucket_type_heap
APU_DECLARE_DATA const apr_bucket_type_t	apr_bucket_type_pool
APU_DECLARE_DATA const apr_bucket_type_t	apr_bucket_type_pipe
APU_DECLARE_DATA const apr_bucket_type_t	apr_bucket_type_immortal
APU_DECLARE_DATA const apr_bucket_type_t	apr_bucket_type_transient
APU_DECLARE_DATA const apr_bucket_type_t	apr_bucket_type_socket
apr_bucket **	b
void *	data
const char *	buf
apr_size_t void(*	free_func )(void *data)
apr_socket_t *	thissock
apr_file_t *	thispipe
apr_off_t	offset
apr_file_t *	fd
int	enabled

Define Documentation

#define APR_BRIGADE_CHECK_CONSISTENCY ( b )

checks the ring pointers in a bucket brigade for consistency. an abort() will be triggered if any inconsistencies are found. note: this is a no-op unless APR_BUCKET_DEBUG is defined.

Parameters:

b	The brigade

Definition at line 304 of file apr_buckets.h.

#define APR_BRIGADE_CONCAT	(	a,
		b
	)

Value:

do {                                    \
        APR_RING_CONCAT(&(a)->list, &(b)->list, apr_bucket, link);      \
        APR_BRIGADE_CHECK_CONSISTENCY((a));                             \
    } while (0)

Concatenate brigade b onto the end of brigade a, leaving brigade b empty

Parameters:

a	The first brigade
b	The second brigade

Definition at line 380 of file apr_buckets.h.

#define APR_BRIGADE_EMPTY ( b ) APR_RING_EMPTY(&(b)->list, apr_bucket, link)

Determine if the bucket brigade is empty

Parameters:

b	The brigade to check

Returns:: true or false

Definition at line 338 of file apr_buckets.h.

#define APR_BRIGADE_FIRST ( b ) APR_RING_FIRST(&(b)->list)

Return the first bucket in a brigade

Parameters:

b	The brigade to query

Returns:: The first bucket in the brigade

Definition at line 345 of file apr_buckets.h.

#define APR_BRIGADE_INSERT_HEAD	(	b,
		e
	)

Value:

do {                            \
        apr_bucket *ap__b = (e);                                        \
        APR_RING_INSERT_HEAD(&(b)->list, ap__b, apr_bucket, link);      \
        APR_BRIGADE_CHECK_CONSISTENCY((b));                             \
    } while (0)

Insert a list of buckets at the front of a brigade

Parameters:

b	The brigade to add to
e	The first bucket in a list of buckets to insert

Definition at line 358 of file apr_buckets.h.

#define APR_BRIGADE_INSERT_TAIL	(	b,
		e
	)

Value:

do {                            \
        apr_bucket *ap__b = (e);                                        \
        APR_RING_INSERT_TAIL(&(b)->list, ap__b, apr_bucket, link);      \
        APR_BRIGADE_CHECK_CONSISTENCY((b));                             \
    } while (0)

Insert a list of buckets at the end of a brigade

Parameters:

b	The brigade to add to
e	The first bucket in a list of buckets to insert

Definition at line 369 of file apr_buckets.h.

#define APR_BRIGADE_LAST ( b ) APR_RING_LAST(&(b)->list)

Return the last bucket in a brigade

Parameters:

b	The brigade to query

Returns:: The last bucket in the brigade

Definition at line 351 of file apr_buckets.h.

#define APR_BRIGADE_PREPEND	(	a,
		b
	)

Value:

do {                                    \
        APR_RING_PREPEND(&(a)->list, &(b)->list, apr_bucket, link);     \
        APR_BRIGADE_CHECK_CONSISTENCY((a));                             \
    } while (0)

Prepend brigade b onto the beginning of brigade a, leaving brigade b empty

Parameters:

a	The first brigade
b	The second brigade

Definition at line 390 of file apr_buckets.h.

#define APR_BRIGADE_SENTINEL ( b ) APR_RING_SENTINEL(&(b)->list, apr_bucket, link)

Wrappers around the RING macros to reduce the verbosity of the code that handles bucket brigades. The magic pointer value that indicates the head of the brigade

Remarks:

This is used to find the beginning and end of the brigade, eg:

      while (e != APR_BRIGADE_SENTINEL(b)) {
          ...
          e = APR_BUCKET_NEXT(e);
      }

Parameters:

b	The brigade

Returns:: The magic pointer value

Definition at line 331 of file apr_buckets.h.

#define APR_BUCKET_ALLOC_SIZE APR_ALIGN_DEFAULT(2*sizeof(apr_bucket_structs))

The amount that apr_bucket_alloc() should allocate in the common case. Note: this is twice as big as apr_bucket_structs to allow breathing room for third-party bucket types.

Definition at line 648 of file apr_buckets.h.

#define APR_BUCKET_BUFF_SIZE 8000

default bucket buffer size - 8KB minus room for memory allocator headers

Definition at line 54 of file apr_buckets.h.

#define APR_BUCKET_CHECK_CONSISTENCY ( e )

checks the brigade a bucket is in for ring consistency. an abort() will be triggered if any inconsistencies are found. note: this is a no-op unless APR_BUCKET_DEBUG is defined.

Parameters:

e	The bucket

Definition at line 311 of file apr_buckets.h.

#define apr_bucket_copy	(	e,
		c
	)	(e)->type->copy(e, c)

Copy a bucket.

Parameters:

e	The bucket to copy
c	Returns a pointer to the new bucket

Definition at line 1100 of file apr_buckets.h.

#define apr_bucket_delete ( e )

Value:

do {                                    \
        APR_BUCKET_REMOVE(e);                                           \
        apr_bucket_destroy(e);                                          \
    } while (0)

Delete a bucket by removing it from its brigade (if any) and then destroying it.

Remarks:

This mainly acts as an aid in avoiding code verbosity. It is the preferred exact equivalent to:

      APR_BUCKET_REMOVE(e);
      apr_bucket_destroy(e);

Parameters:

e	The bucket to delete

Definition at line 1001 of file apr_buckets.h.

#define apr_bucket_destroy ( e )

Value:

do {                                    \
        (e)->type->destroy((e)->data);                                  \
        (e)->free(e);                                                   \
    } while (0)

Free the resources used by a bucket. If multiple buckets refer to the same resource it is freed when the last one goes away.

See also:: apr_bucket_delete()

Parameters:

e	The bucket to destroy

Definition at line 985 of file apr_buckets.h.

#define APR_BUCKET_INIT ( e ) APR_RING_ELEM_INIT((e), link)

Initialize a new bucket's prev/next pointers

Parameters:

e	The bucket to initialize

Definition at line 440 of file apr_buckets.h.

#define APR_BUCKET_INSERT_AFTER	(	a,
		b
	)

Value:

do {                            \
        apr_bucket *ap__a = (a), *ap__b = (b);                          \
        APR_RING_INSERT_AFTER(ap__a, ap__b, link);                      \
        APR_BUCKET_CHECK_CONSISTENCY(ap__a);                            \
    } while (0)

Insert a list of buckets after a specified bucket

Parameters:

a	The bucket to insert after
b	The buckets to insert

Definition at line 411 of file apr_buckets.h.

#define APR_BUCKET_INSERT_BEFORE	(	a,
		b
	)

Value:

do {                            \
        apr_bucket *ap__a = (a), *ap__b = (b);                          \
        APR_RING_INSERT_BEFORE(ap__a, ap__b, link);                     \
        APR_BUCKET_CHECK_CONSISTENCY(ap__a);                            \
    } while (0)

Insert a list of buckets before a specified bucket

Parameters:

a	The bucket to insert before
b	The buckets to insert

Definition at line 400 of file apr_buckets.h.

#define APR_BUCKET_IS_EOS ( e ) ((e)->type == &apr_bucket_type_eos)

Determine if a bucket is an EOS bucket

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 461 of file apr_buckets.h.

#define APR_BUCKET_IS_FILE ( e ) ((e)->type == &apr_bucket_type_file)

Determine if a bucket is a FILE bucket

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 467 of file apr_buckets.h.

#define APR_BUCKET_IS_FLUSH ( e ) ((e)->type == &apr_bucket_type_flush)

Determine if a bucket is a FLUSH bucket

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 455 of file apr_buckets.h.

#define APR_BUCKET_IS_HEAP ( e ) ((e)->type == &apr_bucket_type_heap)

Determine if a bucket is a HEAP bucket

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 485 of file apr_buckets.h.

#define APR_BUCKET_IS_IMMORTAL ( e ) ((e)->type == &apr_bucket_type_immortal)

Determine if a bucket is a IMMORTAL bucket

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 497 of file apr_buckets.h.

#define APR_BUCKET_IS_METADATA ( e ) ((e)->type->is_metadata)

Determine if a bucket contains metadata. An empty bucket is safe to arbitrarily remove if and only if this is false.

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 448 of file apr_buckets.h.

#define APR_BUCKET_IS_PIPE ( e ) ((e)->type == &apr_bucket_type_pipe)

Determine if a bucket is a PIPE bucket

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 473 of file apr_buckets.h.

#define APR_BUCKET_IS_POOL ( e ) ((e)->type == &apr_bucket_type_pool)

Determine if a bucket is a POOL bucket

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 511 of file apr_buckets.h.

#define APR_BUCKET_IS_SOCKET ( e ) ((e)->type == &apr_bucket_type_socket)

Determine if a bucket is a SOCKET bucket

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 479 of file apr_buckets.h.

#define APR_BUCKET_IS_TRANSIENT ( e ) ((e)->type == &apr_bucket_type_transient)

Determine if a bucket is a TRANSIENT bucket

Parameters:

e	The bucket to inspect

Returns:: true or false

Definition at line 491 of file apr_buckets.h.

#define APR_BUCKET_NEXT ( e ) APR_RING_NEXT((e), link)

Get the next bucket in the list

Parameters:

e	The current bucket

Returns:: The next bucket

Definition at line 422 of file apr_buckets.h.

#define APR_BUCKET_PREV ( e ) APR_RING_PREV((e), link)

Get the previous bucket in the list

Parameters:

e	The current bucket

Returns:: The previous bucket

Definition at line 428 of file apr_buckets.h.

#define apr_bucket_read	(	e,
		str,
		len,
		block
	)	(e)->type->read(e, str, len, block)

Read some data from the bucket.

The apr_bucket_read function returns a convenient amount of data from the bucket provided, writing the address and length of the data to the pointers provided by the caller. The function tries as hard as possible to avoid a memory copy.

Buckets are expected to be a member of a brigade at the time they are read.

In typical application code, buckets are read in a loop, and after each bucket is read and processed, it is moved or deleted from the brigade and the next bucket read.

The definition of "convenient" depends on the type of bucket that is being read, and is decided by APR. In the case of memory based buckets such as heap and immortal buckets, a pointer will be returned to the location of the buffer containing the complete contents of the bucket.

Some buckets, such as the socket bucket, might have no concept of length. If an attempt is made to read such a bucket, the apr_bucket_read function will read a convenient amount of data from the socket. The socket bucket is magically morphed into a heap bucket containing the just-read data, and a new socket bucket is inserted just after this heap bucket.

To understand why apr_bucket_read might do this, consider the loop described above to read and process buckets. The current bucket is magically morphed into a heap bucket and returned to the caller. The caller processes the data, and deletes the heap bucket, moving onto the next bucket, the new socket bucket. This process repeats, giving the illusion of a bucket brigade that contains potentially infinite amounts of data. It is up to the caller to decide at what point to stop reading buckets.

Some buckets, such as the file bucket, might have a fixed size, but be significantly larger than is practical to store in RAM in one go. As with the socket bucket, if an attempt is made to read from a file bucket, the file bucket is magically morphed into a heap bucket containing a convenient amount of data read from the current offset in the file. During the read, the offset will be moved forward on the file, and a new file bucket will be inserted directly after the current bucket representing the remainder of the file. If the heap bucket was large enough to store the whole remainder of the file, no more file buckets are inserted, and the file bucket will disappear completely.

The pattern for reading buckets described above does create the illusion that the code is willing to swallow buckets that might be too large for the system to handle in one go. This however is just an illusion: APR will always ensure that large (file) or infinite (socket) buckets are broken into convenient bite sized heap buckets before data is returned to the caller.

There is a potential gotcha to watch for: if buckets are read in a loop, and aren't deleted after being processed, the potentially large bucket will slowly be converted into RAM resident heap buckets. If the file is larger than available RAM, an out of memory condition could be caused if the application is not careful to manage this.

Parameters:

e	The bucket to read from
str	The location to store a pointer to the data in
len	The location to store the amount of data read
block	Whether the read function blocks

Definition at line 1073 of file apr_buckets.h.

#define APR_BUCKET_REMOVE ( e ) APR_RING_REMOVE((e), link)

Remove a bucket from its bucket brigade

Parameters:

e	The bucket to remove

Definition at line 434 of file apr_buckets.h.

#define apr_bucket_setaside	(	e,
		p
	)	(e)->type->setaside(e,p)

Setaside data so that stack data is not destroyed on returning from the function

Parameters:

e	The bucket to setaside
p	The pool to setaside into

Definition at line 1081 of file apr_buckets.h.

#define apr_bucket_split	(	e,
		point
	)	(e)->type->split(e, point)

Split one bucket in two at the point provided.

Once split, the original bucket becomes the first of the two new buckets.

(It is assumed that the bucket is a member of a brigade when this function is called).

Parameters:

e	The bucket to split
point	The offset to split the bucket at

Definition at line 1093 of file apr_buckets.h.

Typedef Documentation

typedef apr_status_t(* apr_brigade_flush)(apr_bucket_brigade *bb, void *ctx)

Function called when a brigade should be flushed

Definition at line 282 of file apr_buckets.h.

typedef struct apr_bucket apr_bucket

See also:: apr_bucket

Definition at line 121 of file apr_buckets.h.

typedef struct apr_bucket_alloc_t apr_bucket_alloc_t

See also:: apr_bucket_alloc_t

Definition at line 123 of file apr_buckets.h.

typedef struct apr_bucket_brigade apr_bucket_brigade

The one-sentence buzzword-laden overview: Bucket brigades represent a complex data stream that can be passed through a layered IO system without unnecessary copying. A longer overview follows...

A bucket brigade is a doubly linked list (ring) of buckets, so we aren't limited to inserting at the front and removing at the end. Buckets are only passed around as members of a brigade, although singleton buckets can occur for short periods of time.

Buckets are data stores of various types. They can refer to data in memory, or part of a file or mmap area, or the output of a process, etc. Buckets also have some type-dependent accessor functions: read, split, copy, setaside, and destroy.

read returns the address and size of the data in the bucket. If the data isn't in memory then it is read in and the bucket changes type so that it can refer to the new location of the data. If all the data doesn't fit in the bucket then a new bucket is inserted into the brigade to hold the rest of it.

split divides the data in a bucket into two regions. After a split the original bucket refers to the first part of the data and a new bucket inserted into the brigade after the original bucket refers to the second part of the data. Reference counts are maintained as necessary.

setaside ensures that the data in the bucket has a long enough lifetime. Sometimes it is convenient to create a bucket referring to data on the stack in the expectation that it will be consumed (output to the network) before the stack is unwound. If that expectation turns out not to be valid, the setaside function is called to move the data somewhere safer.

copy makes a duplicate of the bucket structure as long as it's possible to have multiple references to a single copy of the data itself. Not all bucket types can be copied.

destroy maintains the reference counts on the resources used by a bucket and frees them if necessary.

Note: all of the above functions have wrapper macros (apr_bucket_read(), apr_bucket_destroy(), etc), and those macros should be used rather than using the function pointers directly.

To write a bucket brigade, they are first made into an iovec, so that we don't write too little data at one time. Currently we ignore compacting the buckets into as few buckets as possible, but if we really want good performance, then we need to compact the buckets before we convert to an iovec, or possibly while we are converting to an iovec.

See also:: apr_bucket_brigade

Definition at line 119 of file apr_buckets.h.

typedef struct apr_bucket_file apr_bucket_file

See also:: apr_bucket_file

Definition at line 608 of file apr_buckets.h.

typedef struct apr_bucket_heap apr_bucket_heap

See also:: apr_bucket_heap

Definition at line 539 of file apr_buckets.h.

typedef struct apr_bucket_pool apr_bucket_pool

See also:: apr_bucket_pool

Definition at line 557 of file apr_buckets.h.

typedef struct apr_bucket_refcount apr_bucket_refcount

See also:: apr_bucket_refcount

Definition at line 524 of file apr_buckets.h.

typedef union apr_bucket_structs apr_bucket_structs

See also:: apr_bucket_structs

Definition at line 628 of file apr_buckets.h.

typedef struct apr_bucket_type_t apr_bucket_type_t

See also:: apr_bucket_type_t

Definition at line 126 of file apr_buckets.h.

Enumeration Type Documentation

enum apr_read_type_e

Determines how a bucket or brigade should be read

Enumerator:

APR_BLOCK_READ	block until data becomes available
APR_NONBLOCK_READ	return immediately if no data is available

Definition at line 57 of file apr_buckets.h.

Function Documentation

apr_brigade_flush void apr_brigade_flush void const char __attribute__ ( (format(printf, 4, 5)) )

APU_DECLARE ( apr_bucket_brigade * )

Create a new bucket brigade. The bucket brigade is originally empty.

Parameters:

p	The pool to associate with the brigade. Data is not allocated out of the pool, but a cleanup is registered.
list	The bucket allocator to use

Returns:: The empty bucket brigade

Move the buckets from the tail end of the existing brigade b into the brigade a. If a is NULL a new brigade is created. Buckets from e to the last bucket (inclusively) of brigade b are moved from b to the returned brigade a.

Parameters:

b	The brigade to split
e	The first bucket to move
a	The brigade which should be used for the result or NULL if a new brigade should be created. The brigade a will be cleared if it is not empty.

Returns:: The brigade supplied in a or a new one if a was NULL.

Warning:: Note that this function allocates a new brigade if a is NULL so memory consumption should be carefully considered.

Create a new bucket brigade and move the buckets from the tail end of an existing brigade into the new brigade. Buckets from e to the last bucket (inclusively) of brigade b are moved from b to the returned brigade.

Parameters:

b	The brigade to split
e	The first bucket to move

Returns:: The new brigade

Warning:: Note that this function always allocates a new brigade so memory consumption should be carefully considered.

APU_DECLARE ( apr_status_t )

destroy an entire bucket brigade. This includes destroying all of the buckets within the bucket brigade's bucket list.

Parameters:

b	The bucket brigade to destroy

empty out an entire bucket brigade. This includes destroying all of the buckets within the bucket brigade's bucket list. This is similar to apr_brigade_destroy(), except that it does not deregister the brigade's pool cleanup function.

Parameters:

data	The bucket brigade to clean up

Remarks:: Generally, you should use apr_brigade_destroy(). This function can be useful in situations where you have a single brigade that you wish to reuse many times by destroying all of the buckets in the brigade and putting new buckets into it later.

Partition a bucket brigade at a given offset (in bytes from the start of the brigade). This is useful whenever a filter wants to use known ranges of bytes from the brigade; the ranges can even overlap.

Parameters:

b	The brigade to partition
point	The offset at which to partition the brigade
after_point	Returns a pointer to the first bucket after the partition

Returns:: APR_SUCCESS on success, APR_INCOMPLETE if the contents of the brigade were shorter than point, or an error code.

Remarks:: if APR_INCOMPLETE is returned, after_point will be set to the brigade sentinel.

Return the total length of the brigade.

Parameters:

bb	The brigade to compute the length of
read_all	Read unknown-length buckets to force a size
length	Returns the length of the brigade (up to the end, or up to a bucket read error), or -1 if the brigade has buckets of indeterminate length and read_all is 0.

Take a bucket brigade and store the data in a flat char*

Parameters:

bb	The bucket brigade to create the char* from
c	The char* to write into
len	The maximum length of the char array. On return, it is the actual length of the char array.

Creates a pool-allocated string representing a flat bucket brigade

Parameters:

bb	The bucket brigade to create the char array from
c	On return, the allocated char array
len	On return, the length of the char array.
pool	The pool to allocate the string from.

Split a brigade to represent one LF line.

Parameters:

bbOut	The bucket brigade that will have the LF line appended to.
bbIn	The input bucket brigade to search for a LF-line.
block	The blocking mode to be used to split the line.
maxbytes	The maximum bytes to read. If this many bytes are seen without a LF, the brigade will contain a partial line.

Create an iovec of the elements in a bucket_brigade... return number of elements used. This is useful for writing to a file or to the network efficiently.

Parameters:

b	The bucket brigade to create the iovec from
vec	The iovec to create
nvec	The number of elements in the iovec. On return, it is the number of iovec elements actually filled out.

This function writes a list of strings into a bucket brigade.

Parameters:

b	The bucket brigade to add to
flush	The flush function to use if the brigade is full
ctx	The structure to pass to the flush function
va	A list of strings to add

Returns:: APR_SUCCESS or error code.

This function writes a string into a bucket brigade.

The apr_brigade_write function attempts to be efficient with the handling of heap buckets. Regardless of the amount of data stored inside a heap bucket, heap buckets are a fixed size to promote their reuse.

If an attempt is made to write a string to a brigade that already ends with a heap bucket, this function will attempt to pack the string into the remaining space in the previous heap bucket, before allocating a new heap bucket.

This function always returns APR_SUCCESS, unless a flush function is passed, in which case the return value of the flush function will be returned if used.

Parameters:

b	The bucket brigade to add to
flush	The flush function to use if the brigade is full
ctx	The structure to pass to the flush function
str	The string to add
nbyte	The number of bytes to write

Returns:: APR_SUCCESS or error code

This function writes multiple strings into a bucket brigade.

Parameters:

b	The bucket brigade to add to
flush	The flush function to use if the brigade is full
ctx	The structure to pass to the flush function
vec	The strings to add (address plus length for each)
nvec	The number of entries in iovec

Returns:: APR_SUCCESS or error code

This function writes a string into a bucket brigade.

Parameters:

bb	The bucket brigade to add to
flush	The flush function to use if the brigade is full
ctx	The structure to pass to the flush function
str	The string to add

Returns:: APR_SUCCESS or error code

This function writes a character into a bucket brigade.

Parameters:

b	The bucket brigade to add to
flush	The flush function to use if the brigade is full
ctx	The structure to pass to the flush function
c	The character to add

Returns:: APR_SUCCESS or error code

Evaluate a printf and put the resulting string at the end of the bucket brigade.

Parameters:

b	The brigade to write to
flush	The flush function to use if the brigade is full
ctx	The structure to pass to the flush function
fmt	The format of the string to write
va	The arguments to fill out the format

Returns:: APR_SUCCESS or error code

Decrement the refcount of the data in the bucket. This function should only be called by type-specific bucket destruction functions.

Parameters:

data	The private data pointer from the bucket to be destroyed

Returns:: TRUE or FALSE; TRUE if the reference count is now zero, indicating that the shared resource itself can be destroyed by the caller.

Enable or disable memory-mapping for a FILE bucket (default is enabled)

Parameters:

b	The bucket
enabled	Whether memory-mapping should be enabled

Returns:: APR_SUCCESS normally, or an error code if the operation fails

APU_DECLARE ( apr_bucket * )

Utility function to insert a file (or a segment of a file) onto the end of the brigade. The file is split into multiple buckets if it is larger than the maximum size which can be represented by a single bucket.

Parameters:

bb	the brigade to insert into
f	the file to insert
start	the offset of the start of the segment
len	the length of the segment of the file to insert
p	pool from which file buckets are allocated

Returns:: the last bucket inserted

Initialize a bucket containing reference-counted data that may be shared. The caller must allocate the bucket if necessary and initialize its type-dependent fields, and allocate and initialize its own private data structure. This function should only be called by type-specific bucket creation functions.

Parameters:

b	The bucket to initialize
data	A pointer to the private data structure with the reference count at the start
start	The start of the data in the bucket relative to the private base pointer
length	The length of the data in the bucket

Returns:: The new bucket, or NULL if allocation failed

Create an End of Stream bucket. This indicates that there is no more data coming from down the filter stack. All filters should flush at this point.

Parameters:

list	The freelist from which this bucket should be allocated

Returns:: The new bucket, or NULL if allocation failed

Make the bucket passed in an EOS bucket. This indicates that there is no more data coming from down the filter stack. All filters should flush at this point.

Parameters:

b	The bucket to make into an EOS bucket

Returns:: The new bucket, or NULL if allocation failed

Create a flush bucket. This indicates that filters should flush their data. There is no guarantee that they will flush it, but this is the best we can do.

Parameters:

list	The freelist from which this bucket should be allocated

Returns:: The new bucket, or NULL if allocation failed

Make the bucket passed in a FLUSH bucket. This indicates that filters should flush their data. There is no guarantee that they will flush it, but this is the best we can do.

Parameters:

b	The bucket to make into a FLUSH bucket

Returns:: The new bucket, or NULL if allocation failed

Create a bucket referring to long-lived data.

Parameters:

buf	The data to insert into the bucket
nbyte	The size of the data to insert.
list	The freelist from which this bucket should be allocated

Returns:: The new bucket, or NULL if allocation failed

Make the bucket passed in a bucket refer to long-lived data

Parameters:

b	The bucket to make into a IMMORTAL bucket
buf	The data to insert into the bucket
nbyte	The size of the data to insert.

Returns:: The new bucket, or NULL if allocation failed

Create a bucket referring to data on the stack.

Parameters:

buf	The data to insert into the bucket
nbyte	The size of the data to insert.
list	The freelist from which this bucket should be allocated

Returns:: The new bucket, or NULL if allocation failed

Make the bucket passed in a bucket refer to stack data

Parameters:

b	The bucket to make into a TRANSIENT bucket
buf	The data to insert into the bucket
nbyte	The size of the data to insert.

Returns:: The new bucket, or NULL if allocation failed

Create a bucket referring to memory on the heap. If the caller asks for the data to be copied, this function always allocates 4K of memory so that more data can be added to the bucket without requiring another allocation. Therefore not all the data may be put into the bucket. If copying is not requested then the bucket takes over responsibility for free()ing the memory.

Parameters:

buf	The buffer to insert into the bucket
nbyte	The size of the buffer to insert.
free_func	Function to use to free the data; NULL indicates that the bucket should make a copy of the data
list	The freelist from which this bucket should be allocated

Returns:: The new bucket, or NULL if allocation failed

Make the bucket passed in a bucket refer to heap data

Parameters:

b	The bucket to make into a HEAP bucket
buf	The buffer to insert into the bucket
nbyte	The size of the buffer to insert.
free_func	Function to use to free the data; NULL indicates that the bucket should make a copy of the data

Returns:: The new bucket, or NULL if allocation failed

Create a bucket referring to memory allocated from a pool.

Parameters:

buf	The buffer to insert into the bucket
length	The number of bytes referred to by this bucket
pool	The pool the memory was allocated from
list	The freelist from which this bucket should be allocated

Returns:: The new bucket, or NULL if allocation failed

Make the bucket passed in a bucket refer to pool data

Parameters:

b	The bucket to make into a pool bucket
buf	The buffer to insert into the bucket
length	The number of bytes referred to by this bucket
pool	The pool the memory was allocated from

Returns:: The new bucket, or NULL if allocation failed

Create a bucket referring to a socket.

Parameters:

thissock	The socket to put in the bucket
list	The freelist from which this bucket should be allocated

Returns:: The new bucket, or NULL if allocation failed

Make the bucket passed in a bucket refer to a socket

Parameters:

b	The bucket to make into a SOCKET bucket
thissock	The socket to put in the bucket

Returns:: The new bucket, or NULL if allocation failed

Create a bucket referring to a pipe.

Parameters:

thispipe	The pipe to put in the bucket
list	The freelist from which this bucket should be allocated

Returns:: The new bucket, or NULL if allocation failed

Make the bucket passed in a bucket refer to a pipe

Parameters:

b	The bucket to make into a PIPE bucket
thispipe	The pipe to put in the bucket

Returns:: The new bucket, or NULL if allocation failed

Create a bucket referring to a file.

Parameters:

fd	The file to put in the bucket
offset	The offset where the data of interest begins in the file
len	The amount of data in the file we are interested in
p	The pool into which any needed structures should be created while reading from this file bucket
list	The freelist from which this bucket should be allocated

Returns:: The new bucket, or NULL if allocation failed

Remarks:: If the file is truncated such that the segment of the file referenced by the bucket no longer exists, an attempt to read from the bucket will fail with APR_EOF.; apr_brigade_insert_file() should generally be used to insert files into brigades, since that function can correctly handle large file issues.

Make the bucket passed in a bucket refer to a file

Parameters:

b	The bucket to make into a FILE bucket
fd	The file to put in the bucket
offset	The offset where the data of interest begins in the file
len	The amount of data in the file we are interested in
p	The pool into which any needed structures should be created while reading from this file bucket

Returns:: The new bucket, or NULL if allocation failed

apr_pool_t apr_dbd_t int apr_dbd_prepared_t APU_DECLARE_NONSTD ( apr_status_t )

This function writes an unspecified number of strings into a bucket brigade.

Parameters:

b	The bucket brigade to add to
flush	The flush function to use if the brigade is full
ctx	The structure to pass to the flush function
...	The strings to add

Returns:: APR_SUCCESS or error code

Evaluate a printf and put the resulting string at the end of the bucket brigade.

Parameters:

b	The brigade to write to
flush	The flush function to use if the brigade is full
ctx	The structure to pass to the flush function
fmt	The format of the string to write
...	The arguments to fill out the format

Returns:: APR_SUCCESS or error code

This function simply returns APR_SUCCESS to denote that the bucket does not require anything to happen for its setaside() function. This is appropriate for buckets that have "immortal" data -- the data will live at least as long as the bucket.

Parameters:

data	The bucket to setaside
pool	The pool defining the desired lifetime of the bucket data

Returns:: APR_SUCCESS

A place holder function that signifies that the setaside function was not implemented for this bucket

Parameters:

data	The bucket to setaside
pool	The pool defining the desired lifetime of the bucket data

Returns:: APR_ENOTIMPL

A place holder function that signifies that the split function was not implemented for this bucket

Parameters:

data	The bucket to split
point	The location to split the bucket

Returns:: APR_ENOTIMPL

A place holder function that signifies that the copy function was not implemented for this bucket

Parameters:

e	The bucket to copy
c	Returns a pointer to the new bucket

Returns:: APR_ENOTIMPL

Split a simple bucket into two at the given point. Most non-reference counting buckets that allow multiple references to the same block of data (eg transient and immortal) will use this as their split function without any additional type-specific handling.

Parameters:

b	The bucket to be split
point	The offset of the first byte in the new bucket

Returns:: APR_EINVAL if the point is not within the bucket; APR_ENOMEM if allocation failed; or APR_SUCCESS

Copy a simple bucket. Most non-reference-counting buckets that allow multiple references to the same block of data (eg transient and immortal) will use this as their copy function without any additional type-specific handling.

Parameters:

a	The bucket to copy
b	Returns a pointer to the new bucket

Returns:: APR_ENOMEM if allocation failed; or APR_SUCCESS

Split a bucket into two at the given point, and adjust the refcount to the underlying data. Most reference-counting bucket types will be able to use this function as their split function without any additional type-specific handling.

Parameters:

b	The bucket to be split
point	The offset of the first byte in the new bucket

Returns:: APR_EINVAL if the point is not within the bucket; APR_ENOMEM if allocation failed; or APR_SUCCESS

Copy a refcounted bucket, incrementing the reference count. Most reference-counting bucket types will be able to use this function as their copy function without any additional type-specific handling.

Parameters:

a	The bucket to copy
b	Returns a pointer to the new bucket

Returns:: APR_ENOMEM if allocation failed; or APR_SUCCESS

apr_dbd_pvselect: select using a prepared statement + args

Parameters:

driver	- the driver
pool	- working pool
handle	- the connection
res	- pointer to query results. May point to NULL on entry
statement	- the prepared statement to execute
random	- Whether to support random-access to results
...	- varargs list

Returns:: 0 for success or error code

apr_dbd_pvbquery: query using a prepared statement + binary args

Parameters:

driver	- the driver
pool	- working pool
handle	- the connection
nrows	- number of rows affected.
statement	- the prepared statement to execute
...	- varargs list of binary args

Returns:: 0 for success or error code

apr_dbd_pvbselect: select using a prepared statement + binary args

Parameters:

driver	- the driver
pool	- working pool
handle	- the connection
res	- pointer to query results. May point to NULL on entry
statement	- the prepared statement to execute
random	- Whether to support random-access to results
...	- varargs list of binary args

Returns:: 0 for success or error code

APU_DECLARE_NONSTD ( apr_bucket_alloc_t * )

Create a bucket allocator.

Parameters:

p	This pool's underlying apr_allocator_t is used to allocate memory for the bucket allocator. When the pool is destroyed, the bucket allocator's cleanup routine will free all memory that has been allocated from it.

Remarks:: The reason the allocator gets its memory from the pool's apr_allocator_t rather than from the pool itself is because the bucket allocator will free large memory blocks back to the allocator when it's done with them, thereby preventing memory footprint growth that would occur if we allocated from the pool.

Warning:: The allocator must never be used by more than one thread at a time.

Create a bucket allocator.

Parameters:

allocator This apr_allocator_t is used to allocate both the bucket allocator and all memory handed out by the bucket allocator. The caller is responsible for destroying the bucket allocator and the apr_allocator_t -- no automatic cleanups will happen.

Warning:: The allocator must never be used by more than one thread at a time.

APU_DECLARE_NONSTD ( void )

Destroy a bucket allocator.

Parameters:

list	The allocator to be destroyed

Free memory previously allocated with apr_bucket_alloc().

Parameters:

block The block of memory to be freed.

A place holder function that signifies that this bucket does not need to do anything special to be destroyed. That's only the case for buckets that either have no data (metadata buckets) or buckets whose data pointer points to something that's not a bucket-type-specific structure, as with simple buckets where data points to a string and pipe buckets where data points directly to the apr_file_t.

Parameters:

data	The bucket data to destroy

APU_DECLARE_NONSTD ( void * )

Allocate memory for use by the buckets.

Parameters:

size	The amount to allocate.
list	The allocator from which to allocate the memory.

Variable Documentation

apr_bucket apr_bucket_brigade* a

Definition at line 697 of file apr_buckets.h.

apr_off_t apr_bucket** after_point

Definition at line 727 of file apr_buckets.h.

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_eos

The EOS bucket type. This signifies that there will be no more data, ever. All filters MUST send all data to the next filter when they receive a bucket of this type

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_file

The FILE bucket type. This bucket represents a file on disk

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_flush

There is no apr_bucket_destroy_notimpl, because destruction is required to be implemented (it could be a noop, but only if that makes sense for the bucket type) The flush bucket type. This signifies that all data should be flushed to the next filter. The flush bucket should be sent with the other buckets.

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_heap

The HEAP bucket type. This bucket represents a data allocated from the heap.

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_immortal

The IMMORTAL bucket type. This bucket represents a segment of data that the creator is willing to take responsibility for. The core will do nothing with the data in an immortal bucket

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_pipe

The PIPE bucket type. This bucket represents a pipe to another program.

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_pool

The POOL bucket type. This bucket represents a data that was allocated from a pool. IF this bucket is still available when the pool is cleared, the data is copied on to the heap.

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_socket

The SOCKET bucket type. This bucket represents a socket to another machine

APU_DECLARE_DATA const apr_bucket_type_t apr_bucket_type_transient

The TRANSIENT bucket type. This bucket represents a data allocated off the stack. When the setaside function is called, this data is copied on to the heap

apr_bucket** b

Definition at line 1249 of file apr_buckets.h.

apr_bucket_brigade* bbIn

Definition at line 774 of file apr_buckets.h.

apr_bucket_brigade apr_read_type_e block

Definition at line 774 of file apr_buckets.h.

const char* buf

Definition at line 1375 of file apr_buckets.h.

apr_bucket** c

Definition at line 750 of file apr_buckets.h.

apr_brigade_flush void * ctx

Definition at line 799 of file apr_buckets.h.