11#include "cache.h"
2+ #include "trace2/tr2_tbuf.h"
23#include "trace2/tr2_sid.h"
34
45#define TR2_ENVVAR_PARENT_SID "GIT_TR2_PARENT_SID"
56
67static struct strbuf tr2sid_buf = STRBUF_INIT ;
78static int tr2sid_nr_git_parents ;
89
10+ /*
11+ * Compute the final component of the SID representing the current process.
12+ * This should uniquely identify the process and be a valid filename (to
13+ * allow writing trace2 data to per-process files). It should also be fixed
14+ * length for possible use as a database key.
15+ *
16+ * "<yyyymmdd>T<hhmmss>.<fraction>Z-<host>-<process>"
17+ *
18+ * where <host> is a 9 character string:
19+ * "H<first_8_chars_of_sha1_of_hostname>"
20+ * "Localhost" when no hostname.
21+ *
22+ * where <process> is a 9 character string containing the least signifcant
23+ * 32 bits in the process-id.
24+ * "P<pid>"
25+ * (This is an abribrary choice. On most systems pid_t is a 32 bit value,
26+ * so limit doesn't matter. On larger systems, a truncated value is fine
27+ * for our purposes here.)
28+ */
29+ static void tr2_sid_append_my_sid_component (void )
30+ {
31+ const struct git_hash_algo * algo = & hash_algos [GIT_HASH_SHA1 ];
32+ struct tr2_tbuf tb_now ;
33+ git_hash_ctx ctx ;
34+ pid_t pid = getpid ();
35+ unsigned char hash [GIT_MAX_RAWSZ + 1 ];
36+ char hex [GIT_MAX_HEXSZ + 1 ];
37+ char hostname [HOST_NAME_MAX + 1 ];
38+
39+ tr2_tbuf_utc_datetime (& tb_now );
40+ strbuf_addstr (& tr2sid_buf , tb_now .buf );
41+
42+ strbuf_addch (& tr2sid_buf , '-' );
43+ if (xgethostname (hostname , sizeof (hostname )))
44+ strbuf_add (& tr2sid_buf , "Localhost" , 9 );
45+ else {
46+ algo -> init_fn (& ctx );
47+ algo -> update_fn (& ctx , hostname , strlen (hostname ));
48+ algo -> final_fn (hash , & ctx );
49+ hash_to_hex_algop_r (hex , hash , algo );
50+ strbuf_addch (& tr2sid_buf , 'H' );
51+ strbuf_add (& tr2sid_buf , hex , 8 );
52+ }
53+
54+ strbuf_addf (& tr2sid_buf , "-P%08" PRIx32 , (uint32_t )pid );
55+ }
56+
957/*
1058 * Compute a "unique" session id (SID) for the current process. This allows
1159 * all events from this process to have a single label (much like a PID).
@@ -20,7 +68,6 @@ static int tr2sid_nr_git_parents;
2068 */
2169static void tr2_sid_compute (void )
2270{
23- uint64_t us_now ;
2471 const char * parent_sid ;
2572
2673 if (tr2sid_buf .len )
@@ -38,9 +85,7 @@ static void tr2_sid_compute(void)
3885 tr2sid_nr_git_parents ++ ;
3986 }
4087
41- us_now = getnanotime () / 1000 ;
42- strbuf_addf (& tr2sid_buf , "%" PRIuMAX "-%" PRIdMAX , (uintmax_t )us_now ,
43- (intmax_t )getpid ());
88+ tr2_sid_append_my_sid_component ();
4489
4590 setenv (TR2_ENVVAR_PARENT_SID , tr2sid_buf .buf , 1 );
4691}
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