This patch performs a refactoring to the internals of the profiler in order to
expose a function, profiler_suspend_and_sample_thread, which can be called from a
background thread to suspend, sample the native stack, and then resume the
target passed-in thread.
The interface was designed to expose as few internals of the profiler as
possible, exposing only a single callback which accepts the list of program
counters and stack pointers collected during the backtrace.
A method `profiler_current_thread_id` was also added to get the thread_id of the
current thread, which can then be passed by another thread into
profiler_suspend_sample_thread to sample the stack of that thread.
This is implemented in two parts:
1) Splitting SamplerThread into two classes: Sampler, and SamplerThread.
Sampler was created to extract the core logic from SamplerThread which manages
unix signals on android and linux, as well as suspends the target thread on all
platforms. SamplerThread was then modified to subclass this type, adding the
extra methods and fields required for the creation and management of the actual
Sampler Thread.
Some work was done to ensure that the methods on Sampler would not require
ActivePS to be present, as we intend to sample threads when the profiler is not
active for the Background Hang Reporter.
2) Moving the Tick() logic into the TickController interface.
A TickController interface was added to platform which has 2 methods: Tick and
Backtrace. The Tick method replaces the previous Tick() static method, allowing
it to be overridden by a different consumer of SuspendAndSampleAndResumeThread,
while the Backtrace() method replaces the previous MergeStacksIntoProfile
method, allowing it to be overridden by different consumers of
DoNativeBacktrace.
This interface object is then used to wrap implementation specific data, such as
the ProfilerBuffer, and is threaded through the SuspendAndSampleAndResumeThread
and DoNativeBacktrace methods.
This change added 2 virtual calls to the SamplerThread's critical section, which
I believe should be a small enough overhead that it will not affect profiling
performance. These virtual calls could be avoided using templating, but I
decided that doing so would be unnecessary.
MozReview-Commit-ID: AT48xb2asgV
Given that this basically hogs a core per Firefox process, this code only kicks in if you explicitly select a sub-millisecond resolution.
--HG--
extra : rebase_source : 58ca6f8f6537bc4b809e1634ed177c5d47fd499c
Bug 1359000 moved these functions from GeckoProfiler.h to platform.cpp, which
allowed a lot of follow-up simplifications. But it hurt performance.
This patch moves them back to GeckoProfiler.h and makes them |inline| again.
This required adding a second TLS pointer, sPseudoStack. Comments in the patch
explain why.
--HG--
extra : rebase_source : 4198e32b9e251f4014bce890936f4f85dabeb8ab
This removes the need for PROFILER_LIKELY_MEMORY_CONSTRAINED.
The patch also removes PROFILE_JAVA, USE_FAULTY_LIB, CONFIG_CASE_1,
CONFIG_CASE_2 and replaces all their uses with GP_OS_linux or GP_OS_android.
Finally, the patch removes a bogus |defined(GP_OS_darwin)| condition in
platform-linux-lul.cpp.
--HG--
extra : rebase_source : 77d1c625d65ddf551ab8cd4b962ae48c1a54466c
Currently the profiler mostly uses an array of strings to represent which
features are available and in use. This patch changes the profiler core to use
a uint32_t bitfield, which is a much simpler and faster representation.
(nsProfiler and the profiler add-on still use the array of strings, alas.) The
new ProfilerFeature type defines the values in the bitfield.
One side-effect of this change is that profiler_feature_active() now can be
used to query all features. Previously it was just a subset.
Another side-effect is that profiler_get_available_features() no longer incorrectly
indicates support for Java and stack-walking when they aren't supported. (The
handling of task tracer support is unchanged, because the old code handled it
correctly.)