diff options
Diffstat (limited to 'trace2/tr2_sid.c')
| -rw-r--r-- | trace2/tr2_sid.c | 53 |
1 files changed, 49 insertions, 4 deletions
diff --git a/trace2/tr2_sid.c b/trace2/tr2_sid.c index 984524a43c..5047095478 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" @@ -7,6 +8,53 @@ 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 + * length for possible 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 9 character string containing the least signifcant + * 32 bits in the process-id. + * "P<pid>" + * (This is an abribrary choice. On most systems pid_t is a 32 bit value, + * so limit doesn't matter. On larger systems, a truncated value is fine + * for our purposes here.) + */ +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; + pid_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_addf(&tr2sid_buf, "-P%08"PRIx32, (uint32_t)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 +68,6 @@ 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 +85,7 @@ 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); } |