trace2: convert ctx.thread_name from strbuf to pointer

Convert the `tr2tls_thread_ctx.thread_name` field from a `strbuf`
to a "const char*" pointer.

The `thread_name` field is a constant string that is constructed when
the context is created.  Using a (non-const) `strbuf` structure for it
caused some confusion in the past because it implied that someone
could rename a thread after it was created.  That usage was not
intended.  Change it to a const pointer to make the intent more clear.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
index 37a3163be12110ef9e830eba534d19064408c581..52f9356c6953afa97e0998a2487ef793f4b627bb 100644 (file)
--- a/trace2/tr2_tgt_event.c
+++ b/trace2/tr2_tgt_event.c
@@ -90,7 +90,7 @@ static void event_fmt_prepare(const char *event_name, const char *file,
 
        jw_object_string(jw, "event", event_name);
        jw_object_string(jw, "sid", tr2_sid_get());
-       jw_object_string(jw, "thread", ctx->thread_name.buf);
+       jw_object_string(jw, "thread", ctx->thread_name);
 
        /*
         * In brief mode, only emit <time> on these 2 event types.

diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
index 8cb792488c8feee60df3c0e38301d4008b14c50c..59ca58f862d0607eeff999de08d94ae3c7ae3695 100644 (file)
--- a/trace2/tr2_tgt_perf.c
+++ b/trace2/tr2_tgt_perf.c
@@ -108,7 +108,7 @@ static void perf_fmt_prepare(const char *event_name,
 
        strbuf_addf(buf, "d%d | ", tr2_sid_depth());
        strbuf_addf(buf, "%-*s | %-*s | ", TR2_MAX_THREAD_NAME,
-                   ctx->thread_name.buf, TR2FMT_PERF_MAX_EVENT_NAME,
+                   ctx->thread_name, TR2FMT_PERF_MAX_EVENT_NAME,
                    event_name);
 
        len = buf->len + TR2FMT_PERF_REPO_WIDTH;

diff --git a/trace2/tr2_tls.c b/trace2/tr2_tls.c
index 4f7c516ecb6614c22d92ad95937256f76df4cd23..3a67532aae469d9d4f2df40ceb118c0cded64d4c 100644 (file)
--- a/trace2/tr2_tls.c
+++ b/trace2/tr2_tls.c
@@ -35,6 +35,7 @@ struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_base_name,
                                             uint64_t us_thread_start)
 {
        struct tr2tls_thread_ctx *ctx = xcalloc(1, sizeof(*ctx));
+       struct strbuf buf = STRBUF_INIT;
 
        /*
         * Implicitly "tr2tls_push_self()" to capture the thread's start
@@ -47,12 +48,13 @@ struct tr2tls_thread_ctx *tr2tls_create_self(const char *thread_base_name,
 
        ctx->thread_id = tr2tls_locked_increment(&tr2_next_thread_id);
 
-       strbuf_init(&ctx->thread_name, 0);
+       strbuf_init(&buf, 0);
        if (ctx->thread_id)
-               strbuf_addf(&ctx->thread_name, "th%02d:", ctx->thread_id);
-       strbuf_addstr(&ctx->thread_name, thread_base_name);
-       if (ctx->thread_name.len > TR2_MAX_THREAD_NAME)
-               strbuf_setlen(&ctx->thread_name, TR2_MAX_THREAD_NAME);
+               strbuf_addf(&buf, "th%02d:", ctx->thread_id);
+       strbuf_addstr(&buf, thread_base_name);
+       if (buf.len > TR2_MAX_THREAD_NAME)
+               strbuf_setlen(&buf, TR2_MAX_THREAD_NAME);
+       ctx->thread_name = strbuf_detach(&buf, NULL);
 
        pthread_setspecific(tr2tls_key, ctx);
 
@@ -95,7 +97,7 @@ void tr2tls_unset_self(void)
 
        pthread_setspecific(tr2tls_key, NULL);
 
-       strbuf_release(&ctx->thread_name);
+       free((char *)ctx->thread_name);
        free(ctx->array_us_start);
        free(ctx);
 }
@@ -113,7 +115,7 @@ void tr2tls_pop_self(void)
        struct tr2tls_thread_ctx *ctx = tr2tls_get_self();
 
        if (!ctx->nr_open_regions)
-               BUG("no open regions in thread '%s'", ctx->thread_name.buf);
+               BUG("no open regions in thread '%s'", ctx->thread_name);
 
        ctx->nr_open_regions--;
 }

diff --git a/trace2/tr2_tls.h b/trace2/tr2_tls.h
index 3ac4380d82916fd58930b3243936cc7205388310..65836b1399c4196ca92f3512670616e8d82fc894 100644 (file)
--- a/trace2/tr2_tls.h
+++ b/trace2/tr2_tls.h
@@ -15,7 +15,7 @@
 #define TR2_MAX_THREAD_NAME (24)
 
 struct tr2tls_thread_ctx {
-       struct strbuf thread_name;
+       const char *thread_name;
        uint64_t *array_us_start;
        size_t alloc;
        size_t nr_open_regions; /* plays role of "nr" in ALLOC_GROW */