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/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
* block_processor.h - This file is part of libsquashfs
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef SFQS_BLOCK_PROCESSOR_H
#define SFQS_BLOCK_PROCESSOR_H
#include "sqfs/predef.h"
/**
* @file block_processor.h
*
* @brief Contains declarations for the data block processor.
*/
/**
* @struct sqfs_block_processor_t
*
* @brief Encapsulates a thread pool based block processor.
*
* The actual implementation may even be non-threaded, depending on the
* operating system and compile configuration.
*
* Either way, the instantiated object processes data blocks that can be
* enqueued through @ref sqfs_block_processor_enqueue. The completed blocks
* (compressed and checksumed) are dequeued in the same order and a callback
* is called for each one.
*/
/**
* @enum E_SQFS_BLK_FLAGS
*
* @brief Generic flags that tell the processor what to do with a block and
* flags that the processor sets when it is done with a block.
*/
typedef enum {
/**
* @brief Only calculate checksum, do NOT compress the data.
*/
SQFS_BLK_DONT_COMPRESS = 0x0001,
/**
* @brief Set by compressor worker if the block was actually compressed.
*/
SQFS_BLK_IS_COMPRESSED = 0x0002,
/**
* @brief Do not calculate block checksum.
*/
SQFS_BLK_DONT_CHECKSUM = 0x0004,
/**
* @brief Set by compressor worker if compression failed.
*/
SQFS_BLK_COMPRESS_ERROR = 0x0008,
/**
* @brief Indicates that an equeued block is the first block of a file.
*/
SQFS_BLK_FIRST_BLOCK = 0x0010,
/**
* @brief Indicates that an equeued block is the last block of a file.
*/
SQFS_BLK_LAST_BLOCK = 0x0020,
/**
* @brief Allign the block on disk to device block size.
*
* If set in combination with @ref SQFS_BLK_FIRST_BLOCK, the output
* file is padded to a multiple of the device block size before writing
* the block.
*
* If used with @ref SQFS_BLK_LAST_BLOCK, the output file is padded
* after writing the block.
*/
SQFS_BLK_ALLIGN = 0x0040,
/**
* @brief Indicates that a block is not part of a file but contains
* file tail ends and an entry in the fragment table has to be
* added.
*/
SQFS_BLK_FRAGMENT_BLOCK = 0x0080,
} E_SQFS_BLK_FLAGS;
/**
* @struct sqfs_block_t
*
* @brief Encapsulates a chunk of data to be processed by the block processor.
*/
struct sqfs_block_t {
/**
* @brief Used internally, existing value is ignored and overwritten
* when enqueueing a block.
*/
sqfs_block_t *next;
/**
* @brief Used internally, existing value is ignored and overwritten
* when enqueueing a block.
*/
uint32_t sequence_number;
/**
* @brief Size of the data area.
*/
uint32_t size;
/**
* @brief Checksum of the input data.
*/
uint32_t checksum;
/**
* @brief Data block index within the inode.
*/
uint32_t index;
/**
* @brief The squashfs inode related to this block.
*/
sqfs_inode_generic_t *inode;
/**
* @brief User settable flag field.
*
* A combination of @ref E_SQFS_BLK_FLAGS and custom, user
* settable flags.
*/
uint32_t flags;
/**
* @brief Raw data to be processed.
*/
uint8_t data[];
};
/**
* @brief Signature of a callback function that can is called for each block.
*
* Gets called for each processed block. May be called from a different thread
* than the one that calls enqueue or from the same thread, but only from one
* thread at a time.
*
* Guaranteed to be called on blocks in the order that they are submitted
* to enqueue.
*
* @param user The user pointer passed to @ref sqfs_block_processor_create.
* @param blk The finished block.
*
* @return A non-zero return value is interpreted as fatal error.
*/
typedef int (*sqfs_block_cb)(void *user, sqfs_block_t *blk);
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Create a block processor.
*
* @memberof sqfs_block_processor_t
*
* @param max_block_size The maximum size of a data block. Required for the
* internal scratch buffer used for compressing data.
* @param cmp A pointer to a compressor. If multiple worker threads are used,
* the deep copy function of the compressor is used to create
* several instances that don't interfere with each other.
* @param num_workers The number of worker threads to create.
* @param max_backlog The maximum number of blocks currently in flight. When
* trying to add more, enqueueing blocks until the in-flight
* block count drops below the threshold.
* @param user An arbitrary user pointer to pass to the block callback.
* @param callback A function to call for each finished data block.
*
* @return A pointer to a block processor object on success, NULL on allocation
* failure or on failure to create the worker threads and
* synchronisation primitives.
*/
SQFS_API
sqfs_block_processor_t *sqfs_block_processor_create(size_t max_block_size,
sqfs_compressor_t *cmp,
unsigned int num_workers,
size_t max_backlog,
void *user,
sqfs_block_cb callback);
/**
* @brief Destroy a block processor and free all memory used by it.
*
* @memberof sqfs_block_processor_t
*
* @param proc A pointer to a block processor object.
*/
SQFS_API void sqfs_block_processor_destroy(sqfs_block_processor_t *proc);
/**
* @brief Add a block to be processed.
*
* @memberof sqfs_block_processor_t
*
* The function takes over ownership of the submitted block. It is freed after
* processing and calling the block callback.
*
* @note Even on failure, the workers may still be running and you should still
* call @ref sqfs_block_processor_finish before cleaning up.
*
* @param proc A pointer to a block processor object.
* @param block A poitner to a block to enqueue.
*
* @return Zero on success, an @ref E_SQFS_ERROR value on failure. Depending on
* the implementation used, the failure return value can actually come
* directly from the block callback.
*/
SQFS_API int sqfs_block_processor_enqueue(sqfs_block_processor_t *proc,
sqfs_block_t *block);
/**
* @brief Wait for the workers to finish all in-flight data blocks.
*
* @memberof sqfs_block_processor_t
*
* @param proc A pointer to a block processor object.
*
* @return Zero on success, an @ref E_SQFS_ERROR value on failure. The failure
* return value can either be an error encountered during enqueueing,
* processing or a failure return status from the block callback.
*/
SQFS_API int sqfs_block_processor_finish(sqfs_block_processor_t *proc);
#ifdef __cplusplus
}
#endif
#endif /* SFQS_BLOCK_PROCESSOR_H */
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