From 12230362065b1456901eeba25c2e0d4c9c1cf736 Mon Sep 17 00:00:00 2001 From: Jeff Hostetler Date: Wed, 25 Jul 2018 14:49:37 -0400 Subject: [PATCH] status: deserialization wait Teach `git status --deserialize` to either wait indefintely or immediately fail if the status serialization cache file is stale. Signed-off-by: Jeff Hostetler --- Documentation/config/status.txt | 16 +++++ builtin/commit.c | 59 +++++++++++++++- t/t7522-serialized-status.sh | 52 ++++++++++++++ wt-status-deserialize.c | 119 +++++++++++++++++++++++++++++--- wt-status.h | 12 +++- 5 files changed, 245 insertions(+), 13 deletions(-) diff --git a/Documentation/config/status.txt b/Documentation/config/status.txt index 65cecc12e80c80..af043d7e26f269 100644 --- a/Documentation/config/status.txt +++ b/Documentation/config/status.txt @@ -81,3 +81,19 @@ status.deserializePath:: generated by `--serialize`. This will be overridden by `--deserialize=` on the command line. If the cache file is invalid or stale, git will fall-back and compute status normally. + +status.deserializeWait:: + EXPERIMENTAL, Specifies what `git status --deserialize` should do + if the serialization cache file is stale and whether it should + fall-back and compute status normally. This will be overridden by + `--deserialize-wait=` on the command line. ++ +-- +* `fail` - cause git to exit with an error when the status cache file +is stale; this is intended for testing and debugging. +* `block` - cause git to spin and periodically retry the cache file +every 100 ms; this is intended to help coordinate with another git +instance concurrently computing the cache file. +* `no` - to immediately fall-back if cache file is stale. This is the default. +* `` - time (in tenths of a second) to spin and retry. +-- diff --git a/builtin/commit.c b/builtin/commit.c index aefbcef13ef45a..905f74c6d28b5b 100644 --- a/builtin/commit.c +++ b/builtin/commit.c @@ -182,6 +182,9 @@ static int do_implicit_deserialize = 0; static int do_explicit_deserialize = 0; static char *deserialize_path = NULL; +static enum wt_status_deserialize_wait implicit_deserialize_wait = DESERIALIZE_WAIT__UNSET; +static enum wt_status_deserialize_wait explicit_deserialize_wait = DESERIALIZE_WAIT__UNSET; + /* * --serialize | --serialize= * @@ -247,6 +250,40 @@ static int opt_parse_deserialize(const struct option *opt, const char *arg, int return 0; } +static enum wt_status_deserialize_wait parse_dw(const char *arg) +{ + int tenths; + + if (!strcmp(arg, "fail")) + return DESERIALIZE_WAIT__FAIL; + else if (!strcmp(arg, "block")) + return DESERIALIZE_WAIT__BLOCK; + else if (!strcmp(arg, "no")) + return DESERIALIZE_WAIT__NO; + + /* + * Otherwise, assume it is a timeout in tenths of a second. + * If it contains a bogus value, atol() will return zero + * which is OK. + */ + tenths = atol(arg); + if (tenths < 0) + tenths = DESERIALIZE_WAIT__NO; + return tenths; +} + +static int opt_parse_deserialize_wait(const struct option *opt, + const char *arg, + int unset) +{ + if (unset) + explicit_deserialize_wait = DESERIALIZE_WAIT__UNSET; + else + explicit_deserialize_wait = parse_dw(arg); + + return 0; +} + static int opt_parse_m(const struct option *opt, const char *arg, int unset) { struct strbuf *buf = opt->value; @@ -1550,6 +1587,13 @@ static int git_status_config(const char *k, const char *v, } return 0; } + if (!strcmp(k, "status.deserializewait")) { + if (!v || !*v) + implicit_deserialize_wait = DESERIALIZE_WAIT__UNSET; + else + implicit_deserialize_wait = parse_dw(v); + return 0; + } if (!strcmp(k, "status.showuntrackedfiles")) { if (!v) return config_error_nonbool(k); @@ -1612,6 +1656,9 @@ int cmd_status(int argc, const char **argv, const char *prefix) { OPTION_CALLBACK, 0, "deserialize", NULL, N_("path"), N_("deserialize raw status data from file"), PARSE_OPT_OPTARG, opt_parse_deserialize }, + { OPTION_CALLBACK, 0, "deserialize-wait", NULL, + N_("fail|block|no"), N_("how to wait if status cache file is invalid"), + PARSE_OPT_OPTARG, opt_parse_deserialize_wait }, OPT_SET_INT(0, "long", &status_format, N_("show status in long format (default)"), STATUS_FORMAT_LONG), @@ -1708,11 +1755,21 @@ int cmd_status(int argc, const char **argv, const char *prefix) } if (try_deserialize) { + int result; + enum wt_status_deserialize_wait dw = implicit_deserialize_wait; + if (explicit_deserialize_wait != DESERIALIZE_WAIT__UNSET) + dw = explicit_deserialize_wait; + if (dw == DESERIALIZE_WAIT__UNSET) + dw = DESERIALIZE_WAIT__NO; + if (s.relative_paths) s.prefix = prefix; - if (wt_status_deserialize(&s, deserialize_path) == DESERIALIZE_OK) + result = wt_status_deserialize(&s, deserialize_path, dw); + if (result == DESERIALIZE_OK) return 0; + if (dw == DESERIALIZE_WAIT__FAIL) + die(_("Rejected status serialization cache")); /* deserialize failed, so force the initialization we skipped above. */ enable_fscache(1); diff --git a/t/t7522-serialized-status.sh b/t/t7522-serialized-status.sh index 361afca94835e0..edf15d7af45489 100755 --- a/t/t7522-serialized-status.sh +++ b/t/t7522-serialized-status.sh @@ -199,6 +199,58 @@ test_expect_success 'verify new --serialize=path mode' ' test_cmp expect output.2 ' +test_expect_success 'try deserialize-wait feature' ' + test_when_finished "rm -f serialized_status.dat dirt expect.* output.* trace.*" && + + git status --serialize=serialized_status.dat >output.1 && + + # make status cache stale by updating the mtime on the index. confirm that + # deserialize fails when requested. + sleep 1 && + touch .git/index && + test_must_fail git status --deserialize=serialized_status.dat --deserialize-wait=fail && + test_must_fail git -c status.deserializeWait=fail status --deserialize=serialized_status.dat && + + cat >expect.1 <<-\EOF && + ? expect.1 + ? output.1 + ? serialized_status.dat + ? untracked/ + ? untracked_1.txt + EOF + + # refresh the status cache. + git status --porcelain=v2 --serialize=serialized_status.dat >output.1 && + test_cmp expect.1 output.1 && + + # create some dirt. confirm deserialize used the existing status cache. + echo x >dirt && + git status --porcelain=v2 --deserialize=serialized_status.dat >output.2 && + test_cmp output.1 output.2 && + + # make the cache stale and try the timeout feature and wait upto + # 2 tenths of a second. confirm deserialize timed out and rejected + # the status cache and did a normal scan. + + cat >expect.2 <<-\EOF && + ? dirt + ? expect.1 + ? expect.2 + ? output.1 + ? output.2 + ? serialized_status.dat + ? trace.2 + ? untracked/ + ? untracked_1.txt + EOF + + sleep 1 && + touch .git/index && + GIT_TRACE_DESERIALIZE=1 git status --porcelain=v2 --deserialize=serialized_status.dat --deserialize-wait=2 >output.2 2>trace.2 && + test_cmp expect.2 output.2 && + grep "wait polled=2 result=1" trace.2 >trace.2g +' + test_expect_success 'merge conflicts' ' # create a merge conflict. diff --git a/wt-status-deserialize.c b/wt-status-deserialize.c index bdbb43c3b112fe..fd07919d1afe8f 100644 --- a/wt-status-deserialize.c +++ b/wt-status-deserialize.c @@ -61,7 +61,8 @@ static int my_validate_index(const struct cache_time *mtime_reported) mtime_observed_on_disk.nsec = ST_MTIME_NSEC(st); if ((mtime_observed_on_disk.sec != mtime_reported->sec) || (mtime_observed_on_disk.nsec != mtime_reported->nsec)) { - trace_printf_key(&trace_deserialize, "index mtime changed [des %d.%d][obs %d.%d]", + trace_printf_key(&trace_deserialize, + "index mtime changed [des %d %d][obs %d %d]", mtime_reported->sec, mtime_reported->nsec, mtime_observed_on_disk.sec, mtime_observed_on_disk.nsec); return DESERIALIZE_ERR; @@ -553,6 +554,8 @@ static inline int my_strcmp_null(const char *a, const char *b) static int wt_deserialize_fd(const struct wt_status *cmd_s, struct wt_status *des_s, int fd) { + memset(des_s, 0, sizeof(*des_s)); + /* * Check the path spec on the current command */ @@ -676,8 +679,101 @@ static int wt_deserialize_fd(const struct wt_status *cmd_s, struct wt_status *de return DESERIALIZE_OK; } +static struct cache_time deserialize_prev_mtime = { 0, 0 }; + +static int try_deserialize_read_from_file_1(const struct wt_status *cmd_s, + const char *path, + struct wt_status *des_s) +{ + struct stat st; + int result; + int fd; + + /* + * If we are spinning waiting for the status cache to become + * valid, skip re-reading it if the mtime has not changed + * since the last time we read it. + */ + if (lstat(path, &st)) { + trace_printf_key(&trace_deserialize, + "could not lstat '%s'", path); + return DESERIALIZE_ERR; + } + if (st.st_mtime == deserialize_prev_mtime.sec && + ST_MTIME_NSEC(st) == deserialize_prev_mtime.nsec) { + trace_printf_key(&trace_deserialize, + "mtime has not changed '%s'", path); + return DESERIALIZE_ERR; + } + + fd = xopen(path, O_RDONLY); + if (fd == -1) { + trace_printf_key(&trace_deserialize, + "could not read '%s'", path); + return DESERIALIZE_ERR; + } + + deserialize_prev_mtime.sec = st.st_mtime; + deserialize_prev_mtime.nsec = ST_MTIME_NSEC(st); + + trace_printf_key(&trace_deserialize, + "reading serialization file (%d %d) '%s'", + deserialize_prev_mtime.sec, + deserialize_prev_mtime.nsec, + path); + + result = wt_deserialize_fd(cmd_s, des_s, fd); + close(fd); + + return result; +} + +static int try_deserialize_read_from_file(const struct wt_status *cmd_s, + const char *path, + enum wt_status_deserialize_wait dw, + struct wt_status *des_s) +{ + int k, limit; + int result = DESERIALIZE_ERR; + + /* + * For "fail" or "no", try exactly once to read the status cache. + * Return an error if the file is stale. + */ + if (dw == DESERIALIZE_WAIT__FAIL || dw == DESERIALIZE_WAIT__NO) + return try_deserialize_read_from_file_1(cmd_s, path, des_s); + + /* + * Wait for the status cache file to refresh. Wait duration can + * be in tenths of a second or unlimited. Poll every 100ms. + */ + if (dw == DESERIALIZE_WAIT__BLOCK) { + /* + * Convert "unlimited" to 1 day. + */ + limit = 10 * 60 * 60 * 24; + } else { + /* spin for dw tenths of a second */ + limit = dw; + } + for (k = 0; k < limit; k++) { + result = try_deserialize_read_from_file_1( + cmd_s, path, des_s); + + if (result == DESERIALIZE_OK) + break; + + sleep_millisec(100); + } + + trace_printf_key(&trace_deserialize, + "wait polled=%d result=%d '%s'", + k, result, path); + return result; +} + /* - * Read raw serialized status data from the given file + * Read raw serialized status data from the given file (or STDIN). * * Verify that the args specified in the current command * are compatible with the deserialized data (such as "-uno"). @@ -685,24 +781,25 @@ static int wt_deserialize_fd(const struct wt_status *cmd_s, struct wt_status *de * Copy display-related fields from the current command * into the deserialized data (so that the user can request * long or short as they please). + * + * Print status report using cached data. */ int wt_status_deserialize(const struct wt_status *cmd_s, - const char *path) + const char *path, + enum wt_status_deserialize_wait dw) { struct wt_status des_s; int result; if (path && *path && strcmp(path, "0")) { - int fd = xopen(path, O_RDONLY); - if (fd == -1) { - trace_printf_key(&trace_deserialize, "could not read '%s'", path); - return DESERIALIZE_ERR; - } - trace_printf_key(&trace_deserialize, "reading serialization file '%s'", path); - result = wt_deserialize_fd(cmd_s, &des_s, fd); - close(fd); + result = try_deserialize_read_from_file(cmd_s, path, dw, &des_s); } else { trace_printf_key(&trace_deserialize, "reading stdin"); + + /* + * Read status cache data from stdin. Ignore the deserialize-wait + * term, since we cannot read stdin multiple times. + */ result = wt_deserialize_fd(cmd_s, &des_s, 0); } diff --git a/wt-status.h b/wt-status.h index d7935b2d80d06b..e6843d86068990 100644 --- a/wt-status.h +++ b/wt-status.h @@ -217,6 +217,15 @@ struct wt_status_serialize_data - sizeof(struct wt_status_serialize_data_fixed)]; }; +enum wt_status_deserialize_wait +{ + DESERIALIZE_WAIT__UNSET = -3, + DESERIALIZE_WAIT__FAIL = -2, /* return error, do not fallback */ + DESERIALIZE_WAIT__BLOCK = -1, /* unlimited timeout */ + DESERIALIZE_WAIT__NO = 0, /* immediately fallback */ + /* any positive value is a timeout in tenths of a second */ +}; + /* * Serialize computed status scan results using "version 1" format * to the given file. @@ -231,7 +240,8 @@ void wt_status_serialize_v1(int fd, struct wt_status *s); * fields. */ int wt_status_deserialize(const struct wt_status *cmd_s, - const char *path); + const char *path, + enum wt_status_deserialize_wait dw); /* * A helper routine for serialize and deserialize to compute