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| author | Loïc Hoguin <[email protected]> | 2017-11-17 13:20:14 +0100 |
|---|---|---|
| committer | Loïc Hoguin <[email protected]> | 2017-11-17 13:23:38 +0100 |
| commit | ce5ab4b49ae5b8c0f701334ada48a2e517079e1b (patch) | |
| tree | 4c5feb65c5b1c560f07688743226dda429ec2082 /src/cowboy_tracer_h.erl | |
| parent | 52d869128b28011e0387f1744c8b547faac46cba (diff) | |
| download | cowboy-ce5ab4b49ae5b8c0f701334ada48a2e517079e1b.tar.gz cowboy-ce5ab4b49ae5b8c0f701334ada48a2e517079e1b.tar.bz2 cowboy-ce5ab4b49ae5b8c0f701334ada48a2e517079e1b.zip | |
Initialize trace patterns only once
They are global for the node for all future call trace flags,
so it's not necessary to set them repeatedly with every request.
Doing it once at startup also ensures we can't have race
conditions when the user wants to change which trace patterns
should be used (because requests are concurrent and patterns
end up overwriting themselves repeatedly), and makes this
changing of trace patterns much more straightforward: the
user can just define the ones they want. The default function
traces everything.
In addition I have also added the tracer_flags option to make
the trace flags configurable, excluding the tracer pid.
Diffstat (limited to 'src/cowboy_tracer_h.erl')
| -rw-r--r-- | src/cowboy_tracer_h.erl | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/src/cowboy_tracer_h.erl b/src/cowboy_tracer_h.erl index 914c678..6c6340d 100644 --- a/src/cowboy_tracer_h.erl +++ b/src/cowboy_tracer_h.erl @@ -21,6 +21,8 @@ -export([terminate/3]). -export([early_error/5]). +-export([set_trace_patterns/0]). + -export([tracer_process/3]). -export([system_continue/3]). -export([system_terminate/4]). @@ -66,6 +68,15 @@ terminate(StreamID, Reason, Next) -> early_error(StreamID, Reason, PartialReq, Resp, Opts) -> cowboy_stream:early_error(StreamID, Reason, PartialReq, Resp, Opts). +%% API. + +%% These trace patterns are most likely not suitable for production. +-spec set_trace_patterns() -> ok. +set_trace_patterns() -> + erlang:trace_pattern({'_', '_', '_'}, [{'_', [], [{return_trace}]}], [local]), + erlang:trace_pattern(on_load, [{'_', [], [{return_trace}]}], [local]), + ok. + %% Internal. init_tracer(StreamID, Req, Opts=#{tracer_match_specs := List, tracer_callback := _}) -> @@ -119,12 +130,15 @@ start_tracer(StreamID, Req, Opts) -> case erlang:trace_info(self(), tracer) of {tracer, []} -> TracerPid = proc_lib:spawn_link(?MODULE, tracer_process, [StreamID, Req, Opts]), - erlang:trace_pattern({'_', '_', '_'}, [{'_', [], [{return_trace}]}], [local]), - erlang:trace_pattern(on_load, [{'_', [], [{return_trace}]}], [local]), - erlang:trace(self(), true, [ - send, 'receive', call, return_to, procs, ports, - monotonic_timestamp, set_on_spawn, {tracer, TracerPid} + %% The default flags are probably not suitable for production. + Flags = maps:get(tracer_flags, Opts, [ + send, 'receive', call, return_to, + procs, ports, monotonic_timestamp, + %% The set_on_spawn flag is necessary to catch events + %% from request processes. + set_on_spawn ]), + erlang:trace(self(), true, [{tracer, TracerPid}|Flags]), ok; _ -> ok |