1 // Copyright 2020 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "src/snapshot/snapshot-compression.h"
6
7 #include "src/base/platform/elapsed-timer.h"
8 #include "src/utils/memcopy.h"
9 #include "src/utils/utils.h"
10 #include "third_party/zlib/google/compression_utils_portable.h"
11
12 namespace v8 {
13 namespace internal {
14
GetUncompressedSize(const Bytef * compressed_data)15 uint32_t GetUncompressedSize(const Bytef* compressed_data) {
16 uint32_t size;
17 MemCopy(&size, compressed_data, sizeof(size));
18 return size;
19 }
20
Compress(const SnapshotData * uncompressed_data)21 SnapshotData SnapshotCompression::Compress(
22 const SnapshotData* uncompressed_data) {
23 SnapshotData snapshot_data;
24 base::ElapsedTimer timer;
25 if (FLAG_profile_deserialization) timer.Start();
26
27 static_assert(sizeof(Bytef) == 1, "");
28 const uLongf input_size =
29 static_cast<uLongf>(uncompressed_data->RawData().size());
30 uint32_t payload_length =
31 static_cast<uint32_t>(uncompressed_data->RawData().size());
32
33 uLongf compressed_data_size = compressBound(input_size);
34
35 // Allocating >= the final amount we will need.
36 snapshot_data.AllocateData(
37 static_cast<uint32_t>(sizeof(payload_length) + compressed_data_size));
38
39 byte* compressed_data = const_cast<byte*>(snapshot_data.RawData().begin());
40 // Since we are doing raw compression (no zlib or gzip headers), we need to
41 // manually store the uncompressed size.
42 MemCopy(compressed_data, &payload_length, sizeof(payload_length));
43
44 CHECK_EQ(zlib_internal::CompressHelper(
45 zlib_internal::ZRAW, compressed_data + sizeof(payload_length),
46 &compressed_data_size,
47 bit_cast<const Bytef*>(uncompressed_data->RawData().begin()),
48 input_size, Z_DEFAULT_COMPRESSION, nullptr, nullptr),
49 Z_OK);
50
51 // Reallocating to exactly the size we need.
52 snapshot_data.Resize(static_cast<uint32_t>(compressed_data_size) +
53 sizeof(payload_length));
54 DCHECK_EQ(payload_length,
55 GetUncompressedSize(snapshot_data.RawData().begin()));
56
57 if (FLAG_profile_deserialization) {
58 double ms = timer.Elapsed().InMillisecondsF();
59 PrintF("[Compressing %d bytes took %0.3f ms]\n", payload_length, ms);
60 }
61 return snapshot_data;
62 }
63
Decompress(base::Vector<const byte> compressed_data)64 SnapshotData SnapshotCompression::Decompress(
65 base::Vector<const byte> compressed_data) {
66 SnapshotData snapshot_data;
67 base::ElapsedTimer timer;
68 if (FLAG_profile_deserialization) timer.Start();
69
70 const Bytef* input_bytef = bit_cast<const Bytef*>(compressed_data.begin());
71
72 // Since we are doing raw compression (no zlib or gzip headers), we need to
73 // manually retrieve the uncompressed size.
74 uint32_t uncompressed_payload_length = GetUncompressedSize(input_bytef);
75 input_bytef += sizeof(uncompressed_payload_length);
76
77 snapshot_data.AllocateData(uncompressed_payload_length);
78
79 uLongf uncompressed_size = uncompressed_payload_length;
80 CHECK_EQ(zlib_internal::UncompressHelper(
81 zlib_internal::ZRAW,
82 bit_cast<Bytef*>(snapshot_data.RawData().begin()),
83 &uncompressed_size, input_bytef,
84 static_cast<uLong>(compressed_data.size() -
85 sizeof(uncompressed_payload_length))),
86 Z_OK);
87
88 if (FLAG_profile_deserialization) {
89 double ms = timer.Elapsed().InMillisecondsF();
90 PrintF("[Decompressing %d bytes took %0.3f ms]\n",
91 uncompressed_payload_length, ms);
92 }
93 return snapshot_data;
94 }
95
96 } // namespace internal
97 } // namespace v8
98