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/*
* Copyright (C) Igor Sysoev
* Copyright (C) NGINX, Inc.
*/
#ifndef _NXT_BUF_FILTER_H_INCLUDED_
#define _NXT_BUF_FILTER_H_INCLUDED_
/*
* nxt_buf_filter is a framework intended to simplify processing file
* buffers content by a filter. The filter should set callbacks and
* call nxt_buf_filter_add() to start processing.
*
* At first buf_filter calls filter_ready() and the filter ensures
* it may allocate or reuse its internal buffer. No real allocation
* is performed at this step.
*
* TODO prevent unneeded allocaiton if no input data.
*
*
* TODO: The filter can flush data buffered
* previously, if all internal buffers are full.
*
* Then buf_filter looks buffer chains. There are two buffer chains:
* the input chain is a chain of original incoming memory, file, and sync
* buffers; and the current chain is a chain of memory/file buffers read
* from a file-only buffer. The current chain is processed first. Since
* buffers in this chain always contains a memory part, they can be passed
* one by one to the filter using filter_process(). If there is an output
* buffer after the buffer processing, it is added to output chain. The
* output buffers are not filter internal buffers. They just point to these
* internal buffers and one internal buffer can correspond to several output
* buffers which point to adjoining parts of the internal buffer. Further
* processing depends on filter_process() result code: if it returns NXT_OK,
* then the filter internal buffer is not full and buf_filter looks the next
* current or input buffer. If result code is NXT_AGAIN, then the filter
* internal buffer is full and buf_filter calls filter_flush() and then
* schedules to run nxt_buf_filter_repeat(). nxt_buf_filter_repeat() will
* run after all ready output buffer completion handlers and will call
* buf_filter again if no one completion handler will do it already using
* nxt_buf_filter_enqueue(). So in any case buf_filter will run again only
* once.
*
* TODO:
* in ideal just one the filter internal buffer.
* This allows to minimize number of the filter internal buffers if they
* flush fast.
*
* If the current chain is empty, the buf_filter processes the input chain.
* Memory buffers are passed to the filter using filter_process(). If an
* input buffer is a file buffer, then buf_filter calls filter_flush()
* and starts a file job to read the buffer in memory. The file job reads
* file parts into memory/file buffers and adds them to the current chain.
*
* Sync buffers are passed to the filter using filter_sync(). Its
* post-processing is similar to the filter_process() post-processing,
* except sync buffers are always added unmodified to the output chain.
*/
typedef struct {
nxt_job_file_t job_file;
nxt_buf_pool_t buffers;
} nxt_buf_filter_file_t;
typedef struct nxt_buf_filter_s nxt_buf_filter_t;
typedef struct {
nxt_int_t (*filter_ready)(nxt_buf_filter_t *f);
nxt_int_t (*filter_process)(nxt_buf_filter_t *f);
nxt_int_t (*filter_flush)(nxt_buf_filter_t *f);
nxt_int_t (*filter_sync_nobuf)(nxt_buf_filter_t *f);
nxt_int_t (*filter_sync_flush)(nxt_buf_filter_t *f);
nxt_int_t (*filter_sync_last)(nxt_buf_filter_t *f);
void (*filter_next)(nxt_buf_filter_t *f);
nxt_work_handler_t filter_error;
nxt_buf_filter_file_t *(*job_file_create)(nxt_buf_filter_t *f);
void (*job_file_retain)(nxt_buf_filter_t *f);
void (*job_file_release)(nxt_buf_filter_t *f);
} nxt_buf_filter_ops_t;
struct nxt_buf_filter_s {
nxt_buf_t *current;
nxt_buf_t *input;
nxt_buf_t *output;
nxt_buf_t *last;
nxt_work_queue_t *work_queue;
nxt_buf_filter_file_t *filter_file;
void *data;
nxt_mp_t *mem_pool;
const nxt_buf_filter_ops_t *run;
uint8_t mmap; /* 1 bit */
uint8_t done; /* 1 bit */
uint8_t queued; /* 1 bit */
uint8_t reading; /* 1 bit */
uint8_t buffering; /* 1 bit */
};
NXT_EXPORT void nxt_buf_filter_add(nxt_task_t *task, nxt_buf_filter_t *f,
nxt_buf_t *b);
NXT_EXPORT void nxt_buf_filter(nxt_task_t *task, void *obj, void *data);
NXT_EXPORT void nxt_buf_filter_enqueue(nxt_task_t *task, nxt_buf_filter_t *f);
#endif /* _NXT_BUF_FILTER_H_INCLUDED_ */
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