[PATCH v3 09/10] trace2: make SIDs more unique
- From
- Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>
- Date
- Apr 11, 2019, 15:18 UTC
- Message-ID
- <156ffde4895ac1a64e033341a313ccb3ba7485cd.1554995916.git.gitgitgadget@gmail.com>
- In-Reply-To
- <pull.169.v3.git.gitgitgadget@gmail.com>
From: Jeff Hostetler <jeffhost@microsoft.com>
Update SID component construction to use the current UTC datetime and a portion of the SHA1 of the hostname.
Use an simplified date/time format to make it easier to use the SID component as a logfile filename.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com> --- Documentation/technical/api-trace2.txt | 16 ++++---- trace2/tr2_sid.c | 55 ++++++++++++++++++++++++-- trace2/tr2_tbuf.c | 16 ++++++++ trace2/tr2_tbuf.h | 1 + 4 files changed, 76 insertions(+), 12 deletions(-)
diff --git a/Documentation/technical/api-trace2.txt b/Documentation/technical/api-trace2.txt index cdc00bcc5d..43adbf00eb 100644 --- a/Documentation/technical/api-trace2.txt +++ b/Documentation/technical/api-trace2.txt @@ -78,11 +78,11 @@ git version 2.20.1.155.g426c96fcdb + ------------ $ cat ~/log.event -{"event":"version","sid":"1547659722619736-11614","thread":"main","time":"2019-01-16T17:28:42.620713Z","file":"common-main.c","line":38,"evt":"1","exe":"2.20.1.155.g426c96fcdb"} -{"event":"start","sid":"1547659722619736-11614","thread":"main","time":"2019-01-16T17:28:42.621027Z","file":"common-main.c","line":39,"t_abs":0.001173,"argv":["git","version"]} -{"event":"cmd_name","sid":"1547659722619736-11614","thread":"main","time":"2019-01-16T17:28:42.621122Z","file":"git.c","line":432,"name":"version","hierarchy":"version"} -{"event":"exit","sid":"1547659722619736-11614","thread":"main","time":"2019-01-16T17:28:42.621236Z","file":"git.c","line":662,"t_abs":0.001227,"code":0} -{"event":"atexit","sid":"1547659722619736-11614","thread":"main","time":"2019-01-16T17:28:42.621268Z","file":"trace2/tr2_tgt_event.c","line":163,"t_abs":0.001265,"code":0} +{"event":"version","sid":"sid":"20190408T191610.507018Z-H9b68c35f-P028492","thread":"main","time":"2019-01-16T17:28:42.620713Z","file":"common-main.c","line":38,"evt":"1","exe":"2.20.1.155.g426c96fcdb"} +{"event":"start","sid":"20190408T191610.507018Z-H9b68c35f-P028492","thread":"main","time":"2019-01-16T17:28:42.621027Z","file":"common-main.c","line":39,"t_abs":0.001173,"argv":["git","version"]} +{"event":"cmd_name","sid":"20190408T191610.507018Z-H9b68c35f-P028492","thread":"main","time":"2019-01-16T17:28:42.621122Z","file":"git.c","line":432,"name":"version","hierarchy":"version"} +{"event":"exit","sid":"20190408T191610.507018Z-H9b68c35f-P028492","thread":"main","time":"2019-01-16T17:28:42.621236Z","file":"git.c","line":662,"t_abs":0.001227,"code":0} +{"event":"atexit","sid":"20190408T191610.507018Z-H9b68c35f-P028492","thread":"main","time":"2019-01-16T17:28:42.621268Z","file":"trace2/tr2_tgt_event.c","line":163,"t_abs":0.001265,"code":0} ------------ == Enabling a Target @@ -540,11 +540,11 @@ The following key/value pairs are common to all events: ------------ { "event":"version", - "sid":"1547659722619736-11614", + "sid":"20190408T191827.272759Z-H9b68c35f-P011764", "thread":"main", - "time":"2019-01-16T17:28:42.620713Z", + "time":"2019-04-08T19:18:27.282761Z", "file":"common-main.c", - "line":38, + "line":42, ... } ------------ diff --git a/trace2/tr2_sid.c b/trace2/tr2_sid.c index 984524a43c..68d723bc6c 100644 --- a/trace2/tr2_sid.c +++ b/trace2/tr2_sid.c @@ -1,4 +1,5 @@ #include "cache.h" +#include "trace2/tr2_tbuf.h" #include "trace2/tr2_sid.h" #define TR2_ENVVAR_PARENT_SID "GIT_TR2_PARENT_SID" @@ -6,6 +7,55 @@ static struct strbuf tr2sid_buf = STRBUF_INIT; static int tr2sid_nr_git_parents; +/* + * Compute the final component of the SID representing the current process. + * This should uniquely identify the process and be a valid filename (to + * allow writing trace2 data to per-process files). It should also be fixed + * possible length for use as a database key. + * + * "<yyyymmdd>T<hhmmss>.<fraction>Z-<host>-<process>" + * + * where <host> is a 9 character string: + * "H<first_8_chars_of_sha1_of_hostname>" + * "Localhost" when no hostname. + * + * where <process> is a possibly wrapped PID: + * "P<6-digit-pid>" + * "W<wrapped-6-digit-pid>" when PID too big. + * + */ +static void tr2_sid_append_my_sid_component(void) +{ + const struct git_hash_algo *algo = &hash_algos[GIT_HASH_SHA1]; + struct tr2_tbuf tb_now; + git_hash_ctx ctx; + uintmax_t pid = getpid(); + unsigned char hash[GIT_MAX_RAWSZ + 1]; + char hex[GIT_MAX_HEXSZ + 1]; + char hostname[HOST_NAME_MAX + 1]; + + tr2_tbuf_utc_datetime(&tb_now); + strbuf_addstr(&tr2sid_buf, tb_now.buf); + + strbuf_addch(&tr2sid_buf, '-'); + if (xgethostname(hostname, sizeof(hostname))) + strbuf_add(&tr2sid_buf, "Localhost", 9); + else { + algo->init_fn(&ctx); + algo->update_fn(&ctx, hostname, strlen(hostname)); + algo->final_fn(hash, &ctx); + hash_to_hex_algop_r(hex, hash, algo); + strbuf_addch(&tr2sid_buf, 'H'); + strbuf_add(&tr2sid_buf, hex, 8); + } + + strbuf_addch(&tr2sid_buf, '-'); + if (pid > 999999) + strbuf_addf(&tr2sid_buf, "W%06d", (int)(pid % 1000000)); + else + strbuf_addf(&tr2sid_buf, "P%06d", (int)pid); +} + /* * Compute a "unique" session id (SID) for the current process. This allows * all events from this process to have a single label (much like a PID). @@ -20,7 +70,6 @@ static int tr2sid_nr_git_parents; */ static void tr2_sid_compute(void) { - uint64_t us_now; const char *parent_sid; if (tr2sid_buf.len) @@ -38,9 +87,7 @@ static void tr2_sid_compute(void) tr2sid_nr_git_parents++; } - us_now = getnanotime() / 1000; - strbuf_addf(&tr2sid_buf, "%" PRIuMAX "-%" PRIdMAX, (uintmax_t)us_now, - (intmax_t)getpid()); + tr2_sid_append_my_sid_component(); setenv(TR2_ENVVAR_PARENT_SID, tr2sid_buf.buf, 1); } diff --git a/trace2/tr2_tbuf.c b/trace2/tr2_tbuf.c index eb1b240d8a..c8a19ac341 100644 --- a/trace2/tr2_tbuf.c +++ b/trace2/tr2_tbuf.c @@ -30,3 +30,19 @@ void tr2_tbuf_utc_datetime_extended(struct tr2_tbuf *tb) tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec, (long)tv.tv_usec); } + +void tr2_tbuf_utc_datetime(struct tr2_tbuf *tb) +{ + struct timeval tv; + struct tm tm; + time_t secs; + + gettimeofday(&tv, NULL); + secs = tv.tv_sec; + gmtime_r(&secs, &tm); + + xsnprintf(tb->buf, sizeof(tb->buf), + "%4d%02d%02dT%02d%02d%02d.%06ldZ", tm.tm_year + 1900, + tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec, + (long)tv.tv_usec); +} diff --git a/trace2/tr2_tbuf.h b/trace2/tr2_tbuf.h index 2a1d173ff2..fa853d8f42 100644 --- a/trace2/tr2_tbuf.h +++ b/trace2/tr2_tbuf.h @@ -19,5 +19,6 @@ void tr2_tbuf_local_time(struct tr2_tbuf *tb); * Fill buffer with formatted UTC datatime string. */ void tr2_tbuf_utc_datetime_extended(struct tr2_tbuf *tb); +void tr2_tbuf_utc_datetime(struct tr2_tbuf *tb); #endif /* TR2_TBUF_H */
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