v28.0 - 2022-08-02:
Tracing service and probes:
* Add android.statsd datasource.
* Removed log spam about sys.trace.traced_started in standalone builds.
* Changed kallsyms parsing in traced_probes (ftrace) to be always
synchronous (when starting the trace, rather than on the first batch).
* Added ksyms_mem_policy = KSYMS_RETAIN_FOREVER config to avoid destroying
and re-parsing kallsysm repeatedly in benchmark runs.
* Improve heap profiling shutdown: now the shared memory buffer where
alloc/free records are stored is properly flushed when stopping the data
source.
* Fixed race condition in the daemonization path of perfetto --background.
It would cause daemonization failures if the TTY is destroyed immediately.
Trace Processor:
* Deprecate calling NotifyEndOfFile more than once: Flush should instead be
used for all but the final call.
* Added ingestion and visualization of I2C transactions.
UI:
* Changed callstack sampling selection: selecting one sample now only shows
one stacktrace, selecting multiple samples shows the aggregation.
SDK:
* Fixed a bug (b/239725760) that would cause abstract sockets using the
"@name" syntax in PERFETTO_CONSUMER_SOCK_NAME/PERFETTO_PRODUCER_SOCK_NAME
to have a trailing \0 in the socket name. This breaks interoperability
with adb forwarding. This is a tracing protocol breaking change. Nobody
seems to be relying on @abstract syntax across different versions of
client vs service.
* Changed the mangling scheme for protozero enums nested in another message:
instead of OuterClass_Enum_VALUE, the enum values will be just named
VALUE with the enum itself wrapped in a perfetto_pbzero_enum_OuterClass
namespace to prevent naming collisions. This will allow the users
to alias the enum directly and use throughout their code.
The exact name mangling scheme is a carry-over from libprotobuf and
an internal implementation detail, so nobody should be relying on that.
* Added protozero::EnumToString() to convert enum keys to string literals.
