1 /*
2  * Copyright (c) Facebook, Inc. and its affiliates.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *     http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #pragma once
18 
19 #include <memory.h>
20 
21 #include <folly/Memory.h>
22 #include <folly/Portability.h>
23 #include <folly/compression/Compression.h>
24 
25 #if FOLLY_HAVE_LIBZSTD
26 
27 #ifndef ZSTD_STATIC_LINKING_ONLY
28 #define ZSTD_STATIC_LINKING_ONLY
29 #endif
30 #include <zstd.h>
31 
32 namespace folly {
33 namespace io {
34 namespace zstd {
35 
36 /**
37  * Interface for zstd-specific codec initialization.
38  */
39 class Options {
40  public:
41   /* Create an Options struct with the default options for the given `level`.
42    * NOTE: This is the zstd level, COMPRESSION_LEVEL_DEFAULT and such aren't
43    *       supported, since zstd supports negative compression levels.
44    */
45   explicit Options(int level);
46 
47   /**
48    * Set the compression `param` to `value`.
49    * See the zstd documentation for ZSTD_CCtx_setParameter() for details, this
50    * is just a thin wrapper.
51    */
52   void set(ZSTD_cParameter param, unsigned value);
53 
54   /**
55    * Set the maximum allowed window size during decompression.
56    * `maxWindowSize == 0` means don't set the maximum window size.
57    * zstd's current default limit is 2^27.
58    * See the zstd documentation for ZSTD_DCtx_setMaxWindowSize() for details.
59    */
setMaxWindowSize(size_t maxWindowSize)60   void setMaxWindowSize(size_t maxWindowSize) {
61     maxWindowSize_ = maxWindowSize;
62   }
63 
64   /// Get a reference to the ZSTD_CCtx_params.
params()65   ZSTD_CCtx_params const* params() const { return params_.get(); }
66 
67   /// Get the compression level.
level()68   int level() const { return level_; }
69 
70   /// Get the maximum window size.
maxWindowSize()71   size_t maxWindowSize() const { return maxWindowSize_; }
72 
73  private:
74   static void freeCCtxParams(ZSTD_CCtx_params* params);
75   std::unique_ptr<
76       ZSTD_CCtx_params,
77       folly::static_function_deleter<ZSTD_CCtx_params, &freeCCtxParams>>
78       params_;
79   size_t maxWindowSize_{0};
80   int level_;
81 };
82 
83 /// Get a zstd Codec with the given options.
84 std::unique_ptr<Codec> getCodec(Options options);
85 /// Get a zstd StreamCodec with the given options.
86 std::unique_ptr<StreamCodec> getStreamCodec(Options options);
87 
88 } // namespace zstd
89 } // namespace io
90 } // namespace folly
91 
92 #endif
93