There you go Joonas, I don't always ignore your suggestions! This is
simple patch to allow the user to disable symbol loops in case the
auto-detection fails on some obscure (perhaps OpenBSD) platform. Or in
case the user really wants to trim a few bytes from a library only used
during tracing!
If the tracer encounters an unknown enum value it
ought not to crash. Theis patch replaces the idiom
of looking up a name for an enumerated value directly
from a table by a switch statement. As a bonus we get
warnings from the compiler when the enums are updated
in cairo.
If the tracer's object stack underflows we want to
know about is as soon as possible. This patch adds
checks against the stack overflowing and aborts the
program with an object stack dump if it does.
Support non-Linux systems which don't have a /proc/self/cmdline
by transferring the application name given to cairo-trace via
an environment variable CAIRO_TRACE_PROG_NAME.
cairo_script_context_t is an encapsulation object for interfacing with the
output - multiple surfaces can share the same context, meaning that they
write to the same destination file/stream.
Larry Ewing hit a bug in cairo-trace whereby it tried to create a similar
surface referencing an undefined object. This fix checks whether the
object has yet to be defined, and if not issues an index in order to copy
the appropriate operand from the stack.
font expects the dictionary to be constructed on the stack for its use, so
close it. (I missed the closing '>>' when switching between dictionary
constructors.)
Handling clip as part of the surface state, as opposed to being part of
the operation state, is cumbersome and a hindrance to providing true proxy
surface support. For example, the clip must be copied from the surface
onto the fallback image, but this was forgotten causing undue hassle in
each backend. Another example is the contortion the meta surface
endures to ensure the clip is correctly recorded. By contrast passing the
clip along with the operation is quite simple and enables us to write
generic handlers for providing surface wrappers. (And in the future, we
should be able to write more esoteric wrappers, e.g. automatic 2x FSAA,
trivially.)
In brief, instead of the surface automatically applying the clip before
calling the backend, the backend can call into a generic helper to apply
clipping. For raster surfaces, clip regions are handled automatically as
part of the composite interface. For vector surfaces, a clip helper is
introduced to replay and callback into an intersect_clip_path() function
as necessary.
Whilst this is not primarily a performance related change (the change
should just move the computation of the clip from the moment it is applied
by the user to the moment it is required by the backend), it is important
to track any potential regression:
ppc:
Speedups
========
image-rgba evolution-20090607-0 1026085.22 0.18% -> 672972.07 0.77%: 1.52x speedup
▌
image-rgba evolution-20090618-0 680579.98 0.12% -> 573237.66 0.16%: 1.19x speedup
▎
image-rgba swfdec-fill-rate-4xaa-0 460296.92 0.36% -> 407464.63 0.42%: 1.13x speedup
▏
image-rgba swfdec-fill-rate-2xaa-0 128431.95 0.47% -> 115051.86 0.42%: 1.12x speedup
▏
Slowdowns
=========
image-rgba firefox-periodic-table-0 56837.61 0.78% -> 66055.17 3.20%: 1.09x slowdown
▏
Based on the work by Øyvind Kolås and Pierre Tardy -- many thanks to
Pierre for pushing this backend for inclusion as well as testing and
reviewing my initial patch. And many more thanks to pippin for writing the
backend in the first place!
Hacked and chopped by myself into a suitable basis for a backend. Quite a
few issues remain open, but would seem to be ready for testing on suitable
hardware.
It is easier on the eye to use
'1 index set-source exch pop'
rather than
'dup /p0 exch def p0 set-source /p0 undef'
(as patterns are expected to be temporary so we strive to avoid naming
them).
After opening a specific file or fd for ourselves, reset the
CAIRO_TRACE_FD to point to an invalid fd in order to prevent any child
processes (who inherit our environment) from attempting to trace cairo
calls. If we allow them to continue, then the two traces will intermix
and be unreplayable.
Embed the pixels for images less than 32*32 as this catches most icons
which are frequently uploaded, but is still an unlikely size for a
destination image surface.
Using a null surface is a convenient method to measure the overhead of the
performance testing framework, so export it although as a test-surface so
that it will only be available in development builds and not pollute
distributed libraries.
Need to allow user programs to dump their traces into the common output
directory, when using /etc/ld.so.preload to capture traces for the entire
desktop.
Carl spotted this last night, but I misinterpreted it as an old problem
caused by the application changing its working directory before its first
cairo call - thus causing cairo-trace to attempt to open a file in the new
directory. Instead the problem was attempting to trace an executable with
an absolute path, where we just tagged it with a .lzma extentsion and
attempted to pipe the output there. Obviously this fails for the user
profiling system binaries. So use basename to strip the leading path.
python lazily loads libcairo.so and so it is not available via RTLD_NEXT,
and we need to dlopen cairo ourselves. Similarly the linker is not able to
resolve any naked function references and so we need to ensure that all of
our own calls into the library are wrapped with DLCALL.
Objects like cairo_scaled_font_t may return a reference to a previously
defined scaled-font instead of creating a new token each time. This caused
cairo-trace to overflow its operand stack by pushing a new instance of the
old token every time. Modify the tracer such that a font token can only
appear once on the stack -- for font-faces we remove the old operand and
for scaled-fonts we simply pop, chosen to reflect expected usage.
Applications such as swfdec have a strictly correct use of mark-dirty and
so we need an option to re-enable mark-dirty tracing in conjunction with
--profile.
To save typing when creating macro-benchmarks --profile disables
mark-dirty and caller-info and compresses the trace using LZMA. Not for
computers short on memory!
Record the current working directory and pass that along to cairo-trace so
that the trace output is local to the user and not the application. This
is vital if the application is called via a script that changes directory.
Applications like firefox have a very conservative approach and mark
surfaces dirty before every render. As we record the image data every
time, firefox traces can grow very large with redundant data - so allow
the user to disable mark dirty tracing.
In order to have locale-independent output of decimal values, we need to
manually transform such numbers into strings. As this is a solved problem
for cairo, we adopt _cairo_output_stream_printf() and in particular the
_cairo_dtostr() routine for our own printf processing.
This interferes with the application being traced. It is not clear from
printf(3) whether "%.f" is locale dependent or not - but until we have a
failure do not break applications unnecessarily!
Handle the case of tracing an application that spawns it own graphical
children but using the autonaming facility within cairo-trace. Currently
the traced process tree would all attempt to write to the same file,
creating a broken trace. This means sacrificing the display of the output
name, but allows use for a wider range of applications.
