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Export of internal Abseil changes

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d857e6e1f9b09a3eb5abd890677a98b23346f07a by Abseil Team <absl-team@google.com>:

Simplify internal TryAcquireWithSpinning.

No point declaring the `result` variable: we can just return the results
directly.

PiperOrigin-RevId: 307045800

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421952252bc23be51f47f7d23f3422bad1ed382c by Derek Mauro <dmauro@google.com>:

Add custom sink support for `absl::Format()` through an ADL extension mechanism.

Users can now define
`void AbslFormatFlush(MySink* dest, absl::string_view part)`
to allow `absl::Format()` to append to a custom sink.

PiperOrigin-RevId: 306929052

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c73d5cdb62cd58ea421ed1aeeab78a0ffcfeeefb by Matt Calabrese <calabrese@google.com>:

Internal-only conformance-testing macro ABSL_INTERNAL_ASSERT_CONFORMANCE_OF for compile-time and runtime checks of a specified type, expected properties of that type, and a logically-ordered series of equivalence classes of that type.

PiperOrigin-RevId: 306885512

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a8c2495a07f37d68907855e3f0535bd5c27a3b52 by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 306766753
GitOrigin-RevId: d857e6e1f9b09a3eb5abd890677a98b23346f07a
Change-Id: Ic23c92ac74f9ffcbb2471ff8c6691f4b7b20354b
This commit is contained in:
Abseil Team 2020-04-17 08:13:06 -07:00 • committed by Mark Barolak
parent db5773a721
commit b35973e3e3
16 changed files with 3096 additions and 44 deletions
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12
absl/synchronization/mutex.cc
View file

@ -1439,20 +1439,18 @@ void Mutex::AssertNotHeld() const {
// may spin for a short while if the lock cannot be acquired immediately.
static bool TryAcquireWithSpinning(std::atomic<intptr_t>* mu) {
int c = mutex_globals.spinloop_iterations;
int result = -1; // result of operation: 0=false, 1=true, -1=unknown
do { // do/while somewhat faster on AMD
intptr_t v = mu->load(std::memory_order_relaxed);
if ((v & (kMuReader|kMuEvent)) != 0) { // a reader or tracing -> give up
result = 0;
if ((v & (kMuReader|kMuEvent)) != 0) {
return false; // a reader or tracing -> give up
} else if (((v & kMuWriter) == 0) && // no holder -> try to acquire
mu->compare_exchange_strong(v, kMuWriter | v,
std::memory_order_acquire,
std::memory_order_relaxed)) {
result = 1;
return true;
}
} while (result == -1 && --c > 0);
return result == 1;
} while (--c > 0);
return false;
}
ABSL_XRAY_LOG_ARGS(1) void Mutex::Lock() {