This is like sample but has an "enter/exit" flag with it. This can be
useful when you want to provide tracing instead of sampling. We use a
different frame type so that we can denote that this isn't traditional
sampling, and the flag can be used to find the next exit for the current
enter for calculating durations.
The entire stack trace is provided to make things easier on tools
which may want to deal with indirect functions that were not instrumented
but can be unwound. That may allow for tooling to give the user some
insight that it's not *just* this function entering, but some functions
before it were entered too.
This also adds a SysprofTracer instrument which will preload a
libsysprof-tracer-6.so into the process providing the
__cyg_profile_func_enter() and __cyg_profile_func_leave() hooks.
Really what we want to deal with here is tracking an overlay that we may
need to be able to decode after the fact (in case processes exit or we
need to do post-processing symbol resolution).
For the podman case, that is $some_path mapped to root (/), generally
speaking. For flatpak though, that would have two mappings, one for
/app and another for /usr (possibly more).
While I'm not thrilled to add new frame types for every sort of thing, I
think having this will be relatively useful so we can improve decoding
operations.
This adds SysprofCapturePidRoot which lets us specify a root directory
on the host system for which is the real root (/) of the PID. This can
be useful when reconstructing overlays for containers and you need to
direct access to alternate roots.
The layer gives us some ability to try to deal with overlayfs, albeit at
a very rudimentary level. In most cases I anticipate we just deal with
the main root and ignore overlays until necessary.
Use `errno` instead, which is icky, but given that all of the failure
modes are from POSIX I/O functions, it’s at least in keeping with them.
This is a major API break.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #40
Change `sysprof_capture_reader_read_jitmap()` to return a `const
SysprofCaptureJitmap *` (like the other `read` functions), and add a new
`SysprofCaptureJitmapIter` type to allow easy iteration over the jitmap.
This allows a use of `GHashTable` to be removed from the API. It breaks
the libsysprof-capture API and ABI.
All the callers iterate over the jitmap rather than looking up elements
by key. If that functionality is needed in future, additional API can be
added to allow it on `SysprofCaptureJitmap`.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #40
This changes its API and ABI: it now returns an allocated array of const
strings, rather than an allocated array of allocated strings.
The call sites in the source tree have been adjusted accordingly.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #40
`reader` can be `NULL`, but the `NULL` check was done after potentially
dereferencing it.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #40
It has previously been implicitly pulled in by libsysprof-capture, but
that will change in future.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #40
When trying to build gjs with --werror, I get the following error:
In file included from /nix/store/snc19nr462570ssx03v455p164vyz15s-sysprof-3.36.0-dev/include/sysprof-3/sysprof-capture-condition.h:59,
from /nix/store/snc19nr462570ssx03v455p164vyz15s-sysprof-3.36.0-dev/include/sysprof-3/sysprof-capture.h:66,
from ../gjs/profiler.cpp:53:
/nix/store/snc19nr462570ssx03v455p164vyz15s-sysprof-3.36.0-dev/include/sysprof-3/sysprof-capture-types.h:76:40: error: invalid suffix on literal; C++11 requires a space between literal and string macro [-Werror=literal-suffix]
76 | #define SYSPROF_CAPTURE_ADDRESS_FORMAT "0x%016"G_GINT64_MODIFIER"x"
| ^
cc1plus: all warnings being treated as errors
This brings over some of the techniques from the old memprof design.
Sysprof and memprof shared a lot of code, so it is pretty natural to
bring back the same callgraph view based on memory allocations.
This reuses the StackStash just like it did in memprof. While it
would be nice to reuse some existing tools out there, the fit of
memprof with sysprof is so naturally aligned, it's not really a
big deal to bring back the LD_PRELOAD. The value really comes
from seeing all this stuff together instead of multiple apps.
There are plenty of things we can implement on top of this that
we are not doing yet such as temporary allocations, cross-thread
frees, graphing the heap, and graphing differences between the
heap at to points in time. I'd like all of these things, given
enough time to make them useful.
This is still a bit slow though due to the global lock we take
to access the writer. To improve the speed here we need to get
rid of that lock and head towards a design that allows a thread
to request a new writer from Sysprof and save it in TLS (to be
destroyed when the thread exits).
As we gain in usage, we need to be more careful about using a prefix
that will not collide with other symbols. So version 3 of our ABI will
change to using Sysprof/SYSPROF/sysprof as the various prefixes.
The soname/api version bump will happen later on this branch so that
things are easier to test up until then.
The big thing going on here is that we are going to split up the libraries
a bit better, and remove GObject from the capture library. The libsysprof
library will bring in the capture library statically, so we can export the
symbols we want.
Eventually, we will bump the version to sysprof-3, but not yet.
