This CL changes the histogram creation APIs to take a durable
string view (i.e., a pointer+size pair referring to memory that
the programmer has annotated that it will not be freed) instead
of just an implicit pointer. The HistogramBase class internally
represents the name's length and the histogram's flags using
16 bits in order to not grow the in-memory size of Histogram
objects. The name of the histogram is subsequently exposed by
HistogramBase as a string_view.
This CL updates consumers of the histogram name's to use a
string_view of the name. This removes many string length
calculations and string copy operations. For histograms
allocated in shared memory, it also avoids potential out-of-
bounds reads if the underlying string data is modified or
corrupted such that it no longer has a trailing NUL char
at the end of the string.
Lastly, this CL updates a number of call-sites where the
histogram names were being copied into short-lived string
objects for use as search keys into various containers to
perform the functionality without making any unnecessary
copies.
Low-Coverage-Reason: TRIVIAL_CHANGE Use of string_view instead of string/char* in some error/logging paths have low coverage.
AX-Relnotes: n/a
Bug: 393394360, 40818143
Change-Id: Iee9ee5ae62335b9e7815f4ae11bde4ff80cfd4a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6231451
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Antonio Rivera <antoniori@google.com>
Commit-Queue: Roger McFarlane <rogerm@chromium.org>
Reviewed-by: Etienne Pierre-Doray <etiennep@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1422750}
8952859c39