Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * basebackup_lz4.c
4 : * Basebackup sink implementing lz4 compression.
5 : *
6 : * Portions Copyright (c) 2010-2026, PostgreSQL Global Development Group
7 : *
8 : * IDENTIFICATION
9 : * src/backend/backup/basebackup_lz4.c
10 : *
11 : *-------------------------------------------------------------------------
12 : */
13 : #include "postgres.h"
14 :
15 : #ifdef USE_LZ4
16 : #include <lz4frame.h>
17 : #endif
18 :
19 : #include "backup/basebackup_sink.h"
20 :
21 : #ifdef USE_LZ4
22 :
23 : typedef struct bbsink_lz4
24 : {
25 : /* Common information for all types of sink. */
26 : bbsink base;
27 :
28 : /* Compression level. */
29 : int compresslevel;
30 :
31 : LZ4F_compressionContext_t ctx;
32 : LZ4F_preferences_t prefs;
33 :
34 : /* Number of bytes staged in output buffer. */
35 : size_t bytes_written;
36 : } bbsink_lz4;
37 :
38 : static void bbsink_lz4_begin_backup(bbsink *sink);
39 : static void bbsink_lz4_begin_archive(bbsink *sink, const char *archive_name);
40 : static void bbsink_lz4_archive_contents(bbsink *sink, size_t avail_in);
41 : static void bbsink_lz4_manifest_contents(bbsink *sink, size_t len);
42 : static void bbsink_lz4_end_archive(bbsink *sink);
43 : static void bbsink_lz4_cleanup(bbsink *sink);
44 :
45 : static const bbsink_ops bbsink_lz4_ops = {
46 : .begin_backup = bbsink_lz4_begin_backup,
47 : .begin_archive = bbsink_lz4_begin_archive,
48 : .archive_contents = bbsink_lz4_archive_contents,
49 : .end_archive = bbsink_lz4_end_archive,
50 : .begin_manifest = bbsink_forward_begin_manifest,
51 : .manifest_contents = bbsink_lz4_manifest_contents,
52 : .end_manifest = bbsink_forward_end_manifest,
53 : .end_backup = bbsink_forward_end_backup,
54 : .cleanup = bbsink_lz4_cleanup
55 : };
56 : #endif
57 :
58 : /*
59 : * Create a new basebackup sink that performs lz4 compression.
60 : */
61 : bbsink *
62 3 : bbsink_lz4_new(bbsink *next, pg_compress_specification *compress)
63 : {
64 : #ifndef USE_LZ4
65 : ereport(ERROR,
66 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
67 : errmsg("lz4 compression is not supported by this build")));
68 : return NULL; /* keep compiler quiet */
69 : #else
70 : bbsink_lz4 *sink;
71 : int compresslevel;
72 :
73 : Assert(next != NULL);
74 :
75 3 : compresslevel = compress->level;
76 : Assert(compresslevel >= 0 && compresslevel <= 12);
77 :
78 3 : sink = palloc0_object(bbsink_lz4);
79 3 : *((const bbsink_ops **) &sink->base.bbs_ops) = &bbsink_lz4_ops;
80 3 : sink->base.bbs_next = next;
81 3 : sink->compresslevel = compresslevel;
82 :
83 3 : return &sink->base;
84 : #endif
85 : }
86 :
87 : #ifdef USE_LZ4
88 :
89 : /*
90 : * Begin backup.
91 : */
92 : static void
93 3 : bbsink_lz4_begin_backup(bbsink *sink)
94 : {
95 3 : bbsink_lz4 *mysink = (bbsink_lz4 *) sink;
96 : size_t output_buffer_bound;
97 3 : LZ4F_preferences_t *prefs = &mysink->prefs;
98 :
99 : /* Initialize compressor object. */
100 3 : memset(prefs, 0, sizeof(LZ4F_preferences_t));
101 3 : prefs->frameInfo.blockSizeID = LZ4F_max256KB;
102 3 : prefs->compressionLevel = mysink->compresslevel;
103 :
104 : /*
105 : * We need our own buffer, because we're going to pass different data to
106 : * the next sink than what gets passed to us.
107 : */
108 3 : mysink->base.bbs_buffer = palloc(mysink->base.bbs_buffer_length);
109 :
110 : /*
111 : * Since LZ4F_compressUpdate() requires the output buffer of size equal or
112 : * greater than that of LZ4F_compressBound(), make sure we have the next
113 : * sink's bbs_buffer of length that can accommodate the compressed input
114 : * buffer.
115 : */
116 3 : output_buffer_bound = LZ4F_compressBound(mysink->base.bbs_buffer_length,
117 3 : &mysink->prefs);
118 :
119 : /*
120 : * The buffer length is expected to be a multiple of BLCKSZ, so round up.
121 : */
122 3 : output_buffer_bound = output_buffer_bound + BLCKSZ -
123 : (output_buffer_bound % BLCKSZ);
124 :
125 3 : bbsink_begin_backup(sink->bbs_next, sink->bbs_state, output_buffer_bound);
126 3 : }
127 :
128 : /*
129 : * Prepare to compress the next archive.
130 : */
131 : static void
132 5 : bbsink_lz4_begin_archive(bbsink *sink, const char *archive_name)
133 : {
134 5 : bbsink_lz4 *mysink = (bbsink_lz4 *) sink;
135 : char *lz4_archive_name;
136 : LZ4F_errorCode_t ctxError;
137 : size_t headerSize;
138 :
139 5 : ctxError = LZ4F_createCompressionContext(&mysink->ctx, LZ4F_VERSION);
140 5 : if (LZ4F_isError(ctxError))
141 0 : elog(ERROR, "could not create lz4 compression context: %s",
142 : LZ4F_getErrorName(ctxError));
143 :
144 : /* First of all write the frame header to destination buffer. */
145 5 : headerSize = LZ4F_compressBegin(mysink->ctx,
146 5 : mysink->base.bbs_next->bbs_buffer,
147 5 : mysink->base.bbs_next->bbs_buffer_length,
148 5 : &mysink->prefs);
149 :
150 5 : if (LZ4F_isError(headerSize))
151 0 : elog(ERROR, "could not write lz4 header: %s",
152 : LZ4F_getErrorName(headerSize));
153 :
154 : /*
155 : * We need to write the compressed data after the header in the output
156 : * buffer. So, make sure to update the notion of bytes written to output
157 : * buffer.
158 : */
159 5 : mysink->bytes_written += headerSize;
160 :
161 : /* Add ".lz4" to the archive name. */
162 5 : lz4_archive_name = psprintf("%s.lz4", archive_name);
163 : Assert(sink->bbs_next != NULL);
164 5 : bbsink_begin_archive(sink->bbs_next, lz4_archive_name);
165 5 : pfree(lz4_archive_name);
166 5 : }
167 :
168 : /*
169 : * Compress the input data to the output buffer until we run out of input
170 : * data. Each time the output buffer falls below the compression bound for
171 : * the input buffer, invoke the archive_contents() method for then next sink.
172 : *
173 : * Note that since we're compressing the input, it may very commonly happen
174 : * that we consume all the input data without filling the output buffer. In
175 : * that case, the compressed representation of the current input data won't
176 : * actually be sent to the next bbsink until a later call to this function,
177 : * or perhaps even not until bbsink_lz4_end_archive() is invoked.
178 : */
179 : static void
180 8161 : bbsink_lz4_archive_contents(bbsink *sink, size_t avail_in)
181 : {
182 8161 : bbsink_lz4 *mysink = (bbsink_lz4 *) sink;
183 : size_t compressedSize;
184 : size_t avail_in_bound;
185 :
186 8161 : avail_in_bound = LZ4F_compressBound(avail_in, &mysink->prefs);
187 :
188 : /*
189 : * If the number of available bytes has fallen below the value computed by
190 : * LZ4F_compressBound(), ask the next sink to process the data so that we
191 : * can empty the buffer.
192 : */
193 8161 : if ((mysink->base.bbs_next->bbs_buffer_length - mysink->bytes_written) <
194 : avail_in_bound)
195 : {
196 300 : bbsink_archive_contents(sink->bbs_next, mysink->bytes_written);
197 300 : mysink->bytes_written = 0;
198 : }
199 :
200 : /*
201 : * Compress the input buffer and write it into the output buffer.
202 : */
203 8161 : compressedSize = LZ4F_compressUpdate(mysink->ctx,
204 8161 : mysink->base.bbs_next->bbs_buffer + mysink->bytes_written,
205 8161 : mysink->base.bbs_next->bbs_buffer_length - mysink->bytes_written,
206 8161 : (uint8 *) mysink->base.bbs_buffer,
207 : avail_in,
208 : NULL);
209 :
210 8161 : if (LZ4F_isError(compressedSize))
211 0 : elog(ERROR, "could not compress data: %s",
212 : LZ4F_getErrorName(compressedSize));
213 :
214 : /*
215 : * Update our notion of how many bytes we've written into output buffer.
216 : */
217 8161 : mysink->bytes_written += compressedSize;
218 8161 : }
219 :
220 : /*
221 : * There might be some data inside lz4's internal buffers; we need to get
222 : * that flushed out and also finalize the lz4 frame and then get that forwarded
223 : * to the successor sink as archive content.
224 : *
225 : * Then we can end processing for this archive.
226 : */
227 : static void
228 5 : bbsink_lz4_end_archive(bbsink *sink)
229 : {
230 5 : bbsink_lz4 *mysink = (bbsink_lz4 *) sink;
231 : size_t compressedSize;
232 : size_t lz4_footer_bound;
233 :
234 5 : lz4_footer_bound = LZ4F_compressBound(0, &mysink->prefs);
235 :
236 : Assert(mysink->base.bbs_next->bbs_buffer_length >= lz4_footer_bound);
237 :
238 5 : if ((mysink->base.bbs_next->bbs_buffer_length - mysink->bytes_written) <
239 : lz4_footer_bound)
240 : {
241 0 : bbsink_archive_contents(sink->bbs_next, mysink->bytes_written);
242 0 : mysink->bytes_written = 0;
243 : }
244 :
245 5 : compressedSize = LZ4F_compressEnd(mysink->ctx,
246 5 : mysink->base.bbs_next->bbs_buffer + mysink->bytes_written,
247 5 : mysink->base.bbs_next->bbs_buffer_length - mysink->bytes_written,
248 : NULL);
249 :
250 5 : if (LZ4F_isError(compressedSize))
251 0 : elog(ERROR, "could not end lz4 compression: %s",
252 : LZ4F_getErrorName(compressedSize));
253 :
254 : /* Update our notion of how many bytes we've written. */
255 5 : mysink->bytes_written += compressedSize;
256 :
257 : /* Send whatever accumulated output bytes we have. */
258 5 : bbsink_archive_contents(sink->bbs_next, mysink->bytes_written);
259 5 : mysink->bytes_written = 0;
260 :
261 : /* Release the resources. */
262 5 : LZ4F_freeCompressionContext(mysink->ctx);
263 5 : mysink->ctx = NULL;
264 :
265 : /* Pass on the information that this archive has ended. */
266 5 : bbsink_forward_end_archive(sink);
267 5 : }
268 :
269 : /*
270 : * Manifest contents are not compressed, but we do need to copy them into
271 : * the successor sink's buffer, because we have our own.
272 : */
273 : static void
274 15 : bbsink_lz4_manifest_contents(bbsink *sink, size_t len)
275 : {
276 15 : memcpy(sink->bbs_next->bbs_buffer, sink->bbs_buffer, len);
277 15 : bbsink_manifest_contents(sink->bbs_next, len);
278 15 : }
279 :
280 : /*
281 : * In case the backup fails, make sure we free the compression context by
282 : * calling LZ4F_freeCompressionContext() if needed to avoid memory leak.
283 : */
284 : static void
285 3 : bbsink_lz4_cleanup(bbsink *sink)
286 : {
287 3 : bbsink_lz4 *mysink = (bbsink_lz4 *) sink;
288 :
289 3 : if (mysink->ctx)
290 : {
291 0 : LZ4F_freeCompressionContext(mysink->ctx);
292 0 : mysink->ctx = NULL;
293 : }
294 3 : }
295 :
296 : #endif
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