On 10/6/22 5:05 PM, Ævar Arnfjörð Bjarmason wrote:
On Wed, Oct 05 2022, Junio C Hamano wrote:
"Jeff Hostetler via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes:
From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Convert the `tr2tls_thread_ctx.thread_name` field from a `strbuf`
to a "flex array" at the end of the context structure.
[...]
We don't even need that, AFAICT. My reply at [1] is rather long, but the
tl;dr is that the interface for this API is:
$ git grep '^\s+trace2_thread_start'
Documentation/technical/api-trace2.txt: trace2_thread_start("preload_thread");
builtin/fsmonitor--daemon.c: trace2_thread_start("fsm-health");
builtin/fsmonitor--daemon.c: trace2_thread_start("fsm-listen");
compat/simple-ipc/ipc-unix-socket.c: trace2_thread_start("ipc-worker");
compat/simple-ipc/ipc-unix-socket.c: trace2_thread_start("ipc-accept");
compat/simple-ipc/ipc-win32.c: trace2_thread_start("ipc-server");
t/helper/test-fsmonitor-client.c: trace2_thread_start("hammer");
t/helper/test-simple-ipc.c: trace2_thread_start("multiple");
trace2.h: trace2_thread_start_fl((thread_hint), __FILE__, __LINE__)
And we are taking e.g. "preload_thread" and turning it into strings like
these, and saving it into "struct tr2tls_thread_ctx".
"preload_thread", // main thread
"th01:preload_thread", // 1st thread
"th02:preload_thread" // 2nd thread
[...]
So, we don't need to strdup() and store that "preload_thread" anywhere.
It's already a constant string we have hardcoded in the program. We just
need to save a pointer to it.
Current callers tend to pass a string literal. There's nothing
to say that they will continue to do so in the future.
Then we just format the "%s" or (if ".thread_id" == 0) or "th%02d:%s"
(if ".thread_id" > 0) on-the-fly, the two codepaths that end up using
this are already using strbuf_addf(), so just adding to the format there
is easy.
[...]
But then you'd be formatting this "th%0d:%s" on every message
printer. Whereas we can format it once in the thread-start and
save the extra work -- at the expense of a string buffer in the
thread context.
Granted, the event handlers are generating output lines with many
"%" fields, so they are doing non-trivial amounts of work on every
event, but by using a pre-formatted thread-name, we don't need to
increase that workload.
Jeff
