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Minor comment improvements for compress_lz4

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Author: Tomas Vondra
Reviewed-by: Georgios Kokolatos, Justin Pryzby
Discussion: https://postgr.es/m/33496f7c-3449-1426-d568-63f6bca2ac1f@gmail.com
This commit is contained in:
Tomas Vondra 2023-03-23 17:52:56 +01:00
parent f081a48f9a
commit d0160ca11e
1 changed files with 20 additions and 5 deletions
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23
src/bin/pg_dump/compress_lz4.c
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@ -185,12 +185,15 @@ LZ4File_get_error(CompressFileHandle *CFH)
} }
/* /*
* Prepare an already alloc'ed LZ4File struct for subsequent calls. * Prepare an already alloc'ed LZ4File struct for subsequent calls (either
* compression or decompression).
* *
* It creates the necessary contexts for the operations. When compressing, * It creates the necessary contexts for the operations. When compressing data
* it additionally writes the LZ4 header in the output stream. * (indicated by compressing=true), it additionally writes the LZ4 header in the
* output stream.
* *
* Returns true on success and false on error. * Returns true on success. In case of a failure returns false, and stores the
* error code in fs->errcode.
*/ */
static bool static bool
LZ4File_init(LZ4File *fs, int size, bool compressing) LZ4File_init(LZ4File *fs, int size, bool compressing)
@ -203,9 +206,15 @@ LZ4File_init(LZ4File *fs, int size, bool compressing)
fs->compressing = compressing; fs->compressing = compressing;
fs->inited = true; fs->inited = true;
/* When compressing, write LZ4 header to the output stream. */
if (fs->compressing) if (fs->compressing)
{ {
fs->buflen = LZ4F_compressBound(DEFAULT_IO_BUFFER_SIZE, &fs->prefs); fs->buflen = LZ4F_compressBound(DEFAULT_IO_BUFFER_SIZE, &fs->prefs);
/*
* LZ4F_compressBegin requires a buffer that is greater or equal to
* LZ4F_HEADER_SIZE_MAX. Verify that the requirement is met.
*/
if (fs->buflen < LZ4F_HEADER_SIZE_MAX) if (fs->buflen < LZ4F_HEADER_SIZE_MAX)
fs->buflen = LZ4F_HEADER_SIZE_MAX; fs->buflen = LZ4F_HEADER_SIZE_MAX;
@ -258,6 +267,9 @@ LZ4File_init(LZ4File *fs, int size, bool compressing)
* occurrence of the newline char prior to 'size' bytes. * occurrence of the newline char prior to 'size' bytes.
* *
* Any unread content in the overflow buffer is moved to the beginning. * Any unread content in the overflow buffer is moved to the beginning.
*
* Returns the number of bytes read from the overflow buffer (and copied into
* the 'ptr' buffer), or 0 if the overflow buffer is empty.
*/ */
static int static int
LZ4File_read_overflow(LZ4File *fs, void *ptr, int size, bool eol_flag) LZ4File_read_overflow(LZ4File *fs, void *ptr, int size, bool eol_flag)
@ -297,6 +309,9 @@ LZ4File_read_overflow(LZ4File *fs, void *ptr, int size, bool eol_flag)
* at an overflow buffer within LZ4File. Of course, when the function is * at an overflow buffer within LZ4File. Of course, when the function is
* called, it will first try to consume any decompressed content already * called, it will first try to consume any decompressed content already
* present in the overflow buffer, before decompressing new content. * present in the overflow buffer, before decompressing new content.
*
* Returns the number of bytes of decompressed data copied into the ptr
* buffer, or -1 in case of error.
*/ */
static int static int
LZ4File_read_internal(LZ4File *fs, void *ptr, int ptrsize, bool eol_flag) LZ4File_read_internal(LZ4File *fs, void *ptr, int ptrsize, bool eol_flag)