struct snapshot: store `start` rather than `header_len`
Store a pointer to the start of the actual references within the `packed-refs` contents rather than storing the length of the header. This is more convenient for most users of this field. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Michael Haggerty committed
Jan 24, 2018 at 12:14 UTC
4a2854f77cc913fafc7f3191a61b343280979643
1 file changed
+33
-31
refs/packed-backend.c
+33
-31
@@ -68,17 +68,21 @@ struct snapshot {
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int mmapped;
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/*
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- * The contents of the `packed-refs` file. If the file was
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- * already sorted, this points at the mmapped contents of the
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- * file. If not, this points at heap-allocated memory
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- * containing the contents, sorted. If there were no contents
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- * (e.g., because the file didn't exist), `buf` and `eof` are
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- * both NULL.
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+ * The contents of the `packed-refs` file:
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+ *
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+ * - buf -- a pointer to the start of the memory
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+ * - start -- a pointer to the first byte of actual references
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+ * (i.e., after the header line, if one is present)
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+ * - eof -- a pointer just past the end of the reference
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+ * contents
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+ *
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+ * If the `packed-refs` file was already sorted, `buf` points
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+ * at the mmapped contents of the file. If not, it points at
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+ * heap-allocated memory containing the contents, sorted. If
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+ * there were no contents (e.g., because the file didn't
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+ * exist), `buf`, `start`, and `eof` are all NULL.
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*/
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- char *buf, *eof;
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-
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- /* The size of the header line, if any; otherwise, 0: */
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- size_t header_len;
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+ char *buf, *start, *eof;
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/*
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* What is the peeled state of the `packed-refs` file that
@@ -169,8 +173,7 @@ static void clear_snapshot_buffer(struct snapshot *snapshot)
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} else {
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free(snapshot->buf);
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}
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- snapshot->buf = snapshot->eof = NULL;
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- snapshot->header_len = 0;
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+ snapshot->buf = snapshot->start = snapshot->eof = NULL;
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}
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/*
@@ -319,13 +322,14 @@ static void sort_snapshot(struct snapshot *snapshot)
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size_t len, i;
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char *new_buffer, *dst;
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- pos = snapshot->buf + snapshot->header_len;
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+ pos = snapshot->start;
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eof = snapshot->eof;
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- len = eof - pos;
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- if (!len)
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+ if (pos == eof)
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return;
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+ len = eof - pos;
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+
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/*
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* Initialize records based on a crude estimate of the number
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* of references in the file (we'll grow it below if needed):
@@ -391,9 +395,8 @@ static void sort_snapshot(struct snapshot *snapshot)
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* place:
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*/
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clear_snapshot_buffer(snapshot);
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- snapshot->buf = new_buffer;
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+ snapshot->buf = snapshot->start = new_buffer;
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snapshot->eof = new_buffer + len;
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- snapshot->header_len = 0;
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cleanup:
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free(records);
@@ -442,14 +445,14 @@ static const char *find_end_of_record(const char *p, const char *end)
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*/
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static void verify_buffer_safe(struct snapshot *snapshot)
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{
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- const char *buf = snapshot->buf + snapshot->header_len;
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+ const char *start = snapshot->start;
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const char *eof = snapshot->eof;
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const char *last_line;
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- if (buf == eof)
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+ if (start == eof)
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return;
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- last_line = find_start_of_record(buf, eof - 1);
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+ last_line = find_start_of_record(start, eof - 1);
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if (*(eof - 1) != '\n' || eof - last_line < GIT_SHA1_HEXSZ + 2)
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die_invalid_line(snapshot->refs->path,
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last_line, eof - last_line);
@@ -495,18 +498,19 @@ static int load_contents(struct snapshot *snapshot)
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bytes_read = read_in_full(fd, snapshot->buf, size);
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if (bytes_read < 0 || bytes_read != size)
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die_errno("couldn't read %s", snapshot->refs->path);
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- snapshot->eof = snapshot->buf + size;
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snapshot->mmapped = 0;
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break;
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case MMAP_TEMPORARY:
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case MMAP_OK:
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snapshot->buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
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- snapshot->eof = snapshot->buf + size;
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snapshot->mmapped = 1;
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break;
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}
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close(fd);
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+ snapshot->start = snapshot->buf;
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+ snapshot->eof = snapshot->buf + size;
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+
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return 1;
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}
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@@ -539,7 +543,7 @@ static const char *find_reference_location(struct snapshot *snapshot,
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* preceding records all have reference names that come
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* *before* `refname`.
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*/
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- const char *lo = snapshot->buf + snapshot->header_len;
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+ const char *lo = snapshot->start;
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/*
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* A pointer to a the first character of a record whose
@@ -617,8 +621,7 @@ static struct snapshot *create_snapshot(struct packed_ref_store *refs)
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/* If the file has a header line, process it: */
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if (snapshot->buf < snapshot->eof && *snapshot->buf == '#') {
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struct strbuf tmp = STRBUF_INIT;
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- char *p;
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- const char *eol;
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+ char *p, *eol;
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struct string_list traits = STRING_LIST_INIT_NODUP;
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eol = memchr(snapshot->buf, '\n',
@@ -647,7 +650,7 @@ static struct snapshot *create_snapshot(struct packed_ref_store *refs)
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/* perhaps other traits later as well */
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/* The "+ 1" is for the LF character. */
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- snapshot->header_len = eol + 1 - snapshot->buf;
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+ snapshot->start = eol + 1;
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string_list_clear(&traits, 0);
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strbuf_release(&tmp);
@@ -671,13 +674,12 @@ static struct snapshot *create_snapshot(struct packed_ref_store *refs)
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* We don't want to leave the file mmapped, so we are
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* forced to make a copy now:
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*/
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- size_t size = snapshot->eof -
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- (snapshot->buf + snapshot->header_len);
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+ size_t size = snapshot->eof - snapshot->start;
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char *buf_copy = xmalloc(size);
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- memcpy(buf_copy, snapshot->buf + snapshot->header_len, size);
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+ memcpy(buf_copy, snapshot->start, size);
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clear_snapshot_buffer(snapshot);
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- snapshot->buf = buf_copy;
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+ snapshot->buf = snapshot->start = buf_copy;
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snapshot->eof = buf_copy + size;
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}
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@@ -937,7 +939,7 @@ static struct ref_iterator *packed_ref_iterator_begin(
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if (prefix && *prefix)
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start = find_reference_location(snapshot, prefix, 0);
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else
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- start = snapshot->buf + snapshot->header_len;
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+ start = snapshot->start;
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iter->pos = start;
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iter->eof = snapshot->eof;