xref: /freebsd/sys/contrib/openzfs/module/zstd/lib/common/pool.h (revision 187d8a3ce55a4e2d41fbe61465d5ff4ac0fc6bd5)
1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-only
2 /*
3  * Copyright (c) Meta Platforms, Inc. and affiliates.
4  * All rights reserved.
5  *
6  * This source code is licensed under both the BSD-style license (found in the
7  * LICENSE file in the root directory of this source tree) and the GPLv2 (found
8  * in the COPYING file in the root directory of this source tree).
9  * You may select, at your option, one of the above-listed licenses.
10  */
11 
12 #ifndef POOL_H
13 #define POOL_H
14 
15 
16 #include "zstd_deps.h"
17 #define ZSTD_STATIC_LINKING_ONLY   /* ZSTD_customMem */
18 #include "../zstd.h"
19 
20 typedef struct POOL_ctx_s POOL_ctx;
21 
22 /*! POOL_create() :
23  *  Create a thread pool with at most `numThreads` threads.
24  * `numThreads` must be at least 1.
25  *  The maximum number of queued jobs before blocking is `queueSize`.
26  * @return : POOL_ctx pointer on success, else NULL.
27 */
28 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize);
29 
30 POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize,
31                                ZSTD_customMem customMem);
32 
33 /*! POOL_free() :
34  *  Free a thread pool returned by POOL_create().
35  */
36 void POOL_free(POOL_ctx* ctx);
37 
38 
39 /*! POOL_joinJobs() :
40  *  Waits for all queued jobs to finish executing.
41  */
42 void POOL_joinJobs(POOL_ctx* ctx);
43 
44 /*! POOL_resize() :
45  *  Expands or shrinks pool's number of threads.
46  *  This is more efficient than releasing + creating a new context,
47  *  since it tries to preserve and reuse existing threads.
48  * `numThreads` must be at least 1.
49  * @return : 0 when resize was successful,
50  *           !0 (typically 1) if there is an error.
51  *    note : only numThreads can be resized, queueSize remains unchanged.
52  */
53 int POOL_resize(POOL_ctx* ctx, size_t numThreads);
54 
55 /*! POOL_sizeof() :
56  * @return threadpool memory usage
57  *  note : compatible with NULL (returns 0 in this case)
58  */
59 size_t POOL_sizeof(const POOL_ctx* ctx);
60 
61 /*! POOL_function :
62  *  The function type that can be added to a thread pool.
63  */
64 typedef void (*POOL_function)(void*);
65 
66 /*! POOL_add() :
67  *  Add the job `function(opaque)` to the thread pool. `ctx` must be valid.
68  *  Possibly blocks until there is room in the queue.
69  *  Note : The function may be executed asynchronously,
70  *         therefore, `opaque` must live until function has been completed.
71  */
72 void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque);
73 
74 
75 /*! POOL_tryAdd() :
76  *  Add the job `function(opaque)` to thread pool _if_ a queue slot is available.
77  *  Returns immediately even if not (does not block).
78  * @return : 1 if successful, 0 if not.
79  */
80 int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque);
81 
82 #endif
83