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dropped unused SpinLockWait function

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This commit is contained in:
Aliaksey Kandratsenka 2015-09-28 15:40:15 -07:00 committed by Aliaksey Kandratsenka
parent 5b62d38329
commit 3a054d37c1
3 changed files with 1 additions and 35 deletions
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2
src/base/spinlock.cc
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@ -114,7 +114,7 @@ void SpinLock::SlowLock() {
kSpinLockSleeper);
if (lock_value == kSpinLockHeld) {
// Successfully transitioned to kSpinLockSleeper. Pass
// kSpinLockSleeper to the SpinLockWait routine to properly indicate
// kSpinLockSleeper to the SpinLockDelay routine to properly indicate
// the last lock_value observed.
lock_value = kSpinLockSleeper;
} else if (lock_value == kSpinLockFree) {

20
src/base/spinlock_internal.cc
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@ -57,26 +57,6 @@ namespace base { namespace internal { static int SuggestedDelayNS(int loop); }}
namespace base {
namespace internal {
// See spinlock_internal.h for spec.
int32 SpinLockWait(volatile Atomic32 *w, int n,
const SpinLockWaitTransition trans[]) {
int32 v;
bool done = false;
for (int loop = 0; !done; loop++) {
v = base::subtle::Acquire_Load(w);
int i;
for (i = 0; i != n && v != trans[i].from; i++) {
}
if (i == n) {
SpinLockDelay(w, v, loop); // no matching transition
} else if (trans[i].to == v || // null transition
base::subtle::Acquire_CompareAndSwap(w, v, trans[i].to) == v) {
done = trans[i].done;
}
}
return v;
}
// Return a suggested delay in nanoseconds for iteration number "loop"
static int SuggestedDelayNS(int loop) {
// Weak pseudo-random number generator to get some spread between threads

14
src/base/spinlock_internal.h
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@ -43,20 +43,6 @@
namespace base {
namespace internal {
// SpinLockWait() waits until it can perform one of several transitions from
// "from" to "to". It returns when it performs a transition where done==true.
struct SpinLockWaitTransition {
int32 from;
int32 to;
bool done;
};
// Wait until *w can transition from trans[i].from to trans[i].to for some i
// satisfying 0<=i<n && trans[i].done, atomically make the transition,
// then return the old value of *w. Make any other atomic tranistions
// where !trans[i].done, but continue waiting.
int32 SpinLockWait(volatile Atomic32 *w, int n,
const SpinLockWaitTransition trans[]);
void SpinLockWake(volatile Atomic32 *w, bool all);
void SpinLockDelay(volatile Atomic32 *w, int32 value, int loop);