Commit c047317e400efc75b07aa0fff61ee1fcd794e74e
2014-03-18T17:54:32
config: make refresh atomic Current code sets the active map to a new one and builds it whilst it's active. This is a race condition with someone else trying to access the same config. Instead, let's build up our new map and swap the active and new one.
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diff --git a/src/config_file.c b/src/config_file.c
index fcf9cab..437a5c5 100644
--- a/src/config_file.c
+++ b/src/config_file.c
@@ -107,7 +107,7 @@ typedef struct {
diskfile_backend *snapshot_from;
} diskfile_readonly_backend;
-static int config_parse(diskfile_backend *cfg_file, struct reader *reader, git_config_level_t level, int depth);
+static int config_parse(git_strmap *values, diskfile_backend *cfg_file, struct reader *reader, git_config_level_t level, int depth);
static int parse_variable(struct reader *reader, char **var_name, char **var_value);
static int config_write(diskfile_backend *cfg, const char *key, const regex_t *preg, const char *value);
static char *escape_value(const char *ptr);
@@ -243,7 +243,7 @@ static int config_open(git_config_backend *cfg, git_config_level_t level)
if (res == GIT_ENOTFOUND)
return 0;
- if (res < 0 || (res = config_parse(b, reader, level, 0)) < 0) {
+ if (res < 0 || (res = config_parse(b->header.values, b, reader, level, 0)) < 0) {
free_vars(b->header.values);
b->header.values = NULL;
}
@@ -256,47 +256,41 @@ static int config_open(git_config_backend *cfg, git_config_level_t level)
static int config_refresh(git_config_backend *cfg)
{
- int res = 0, updated = 0, any_updated = 0;
+ int error = 0, updated = 0, any_updated = 0;
diskfile_backend *b = (diskfile_backend *)cfg;
- git_strmap *old_values;
+ git_strmap *values = NULL;
struct reader *reader = NULL;
uint32_t i;
for (i = 0; i < git_array_size(b->readers); i++) {
reader = git_array_get(b->readers, i);
-
- res = git_futils_readbuffer_updated(
+ error = git_futils_readbuffer_updated(
&reader->buffer, reader->file_path,
&reader->file_mtime, &reader->file_size, &updated);
- if (res < 0)
- return (res == GIT_ENOTFOUND) ? 0 : res;
+ if (error < 0)
+ return (error == GIT_ENOTFOUND) ? 0 : error;
if (updated)
any_updated = 1;
}
if (!any_updated)
- return (res == GIT_ENOTFOUND) ? 0 : res;
+ return (error == GIT_ENOTFOUND) ? 0 : error;
- /* need to reload - store old values and prep for reload */
- old_values = b->header.values;
- if ((res = git_strmap_alloc(&b->header.values)) < 0) {
- b->header.values = old_values;
+
+ if ((error = git_strmap_alloc(&values)) < 0)
goto cleanup;
- }
- if ((res = config_parse(b, reader, b->level, 0)) < 0) {
- free_vars(b->header.values);
- b->header.values = old_values;
+ if ((error = config_parse(values, b, reader, b->level, 0)) < 0)
goto cleanup;
- }
- free_vars(old_values);
+ values = git__swap(b->header.values, values);
cleanup:
+ free_vars(values);
git_buf_free(&reader->buffer);
- return res;
+ return error;
}
static void backend_free(git_config_backend *_backend)
@@ -1218,7 +1212,7 @@ static int included_path(git_buf *out, const char *dir, const char *path)
return git_path_join_unrooted(out, path, dir, NULL);
}
-static int config_parse(diskfile_backend *cfg_file, struct reader *reader, git_config_level_t level, int depth)
+static int config_parse(git_strmap *values, diskfile_backend *cfg_file, struct reader *reader, git_config_level_t level, int depth)
{
int c;
char *current_section = NULL;
@@ -1228,7 +1222,6 @@ static int config_parse(diskfile_backend *cfg_file, struct reader *reader, git_c
git_buf buf = GIT_BUF_INIT;
int result = 0;
uint32_t reader_idx;
- git_strmap *values = cfg_file->header.values;
if (depth >= MAX_INCLUDE_DEPTH) {
giterr_set(GITERR_CONFIG, "Maximum config include depth reached");
@@ -1327,7 +1320,7 @@ static int config_parse(diskfile_backend *cfg_file, struct reader *reader, git_c
&r->file_size, NULL)) < 0)
break;
- result = config_parse(cfg_file, r, level, depth+1);
+ result = config_parse(values, cfg_file, r, level, depth+1);
r = git_array_get(cfg_file->readers, index);
git_buf_free(&r->buffer);