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authorwin7-7 <win7-7@users.noreply.github.com>2019-05-24 13:58:13 +0300
committerGitHub <noreply@github.com>2019-05-24 13:58:13 +0300
commitddff63b2d6c22468cd413c16968558f77fd00bb3 (patch)
tree4c6d864909cd8a9677ded9d0c4f2d3864230e7a0
parenta3434ba005b8eaa52fdcdfc3392b640f25f10410 (diff)
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add main thread only cache for nsIAtoms to speed up atomization xpcom/ds
add main thread only cache for nsIAtoms to speed up atomization
-rw-r--r--xpcom/ds/nsAtomTable.cpp54
-rw-r--r--xpcom/ds/nsIAtom.idl5
2 files changed, 57 insertions, 2 deletions
diff --git a/xpcom/ds/nsAtomTable.cpp b/xpcom/ds/nsAtomTable.cpp
index 3dd3bd36c..c63676455 100644
--- a/xpcom/ds/nsAtomTable.cpp
+++ b/xpcom/ds/nsAtomTable.cpp
@@ -364,17 +364,31 @@ static const PLDHashTableOps AtomTableOps = {
//----------------------------------------------------------------------
+#define RECENTLY_USED_MAIN_THREAD_ATOM_CACHE_SIZE 31
+static nsIAtom*
+ sRecentlyUsedMainThreadAtoms[RECENTLY_USED_MAIN_THREAD_ATOM_CACHE_SIZE] = {};
+
+
void
DynamicAtom::GCAtomTable()
{
- MutexAutoLock lock(*gAtomTableLock);
- GCAtomTableLocked(lock, GCKind::RegularOperation);
+ if (NS_IsMainThread()) {
+ MutexAutoLock lock(*gAtomTableLock);
+ GCAtomTableLocked(lock, GCKind::RegularOperation);
+ }
}
void
DynamicAtom::GCAtomTableLocked(const MutexAutoLock& aProofOfLock,
GCKind aKind)
{
+
+ MOZ_ASSERT(NS_IsMainThread());
+ for (uint32_t i = 0; i < RECENTLY_USED_MAIN_THREAD_ATOM_CACHE_SIZE; ++i) {
+ sRecentlyUsedMainThreadAtoms[i] = nullptr;
+ }
+
+
uint32_t removedCount = 0; // Use a non-atomic temporary for cheaper increments.
nsAutoCString nonZeroRefcountAtoms;
uint32_t nonZeroRefcountAtomsCount = 0;
@@ -673,6 +687,8 @@ NS_Atomize(const nsACString& aUTF8String)
return atom.forget();
}
+
+
// This results in an extra addref/release of the nsStringBuffer.
// Unfortunately there doesn't seem to be any APIs to avoid that.
// Actually, now there is, sort of: ForgetSharedBuffer.
@@ -712,6 +728,40 @@ NS_Atomize(const nsAString& aUTF16String)
return atom.forget();
}
+already_AddRefed<nsIAtom>
+NS_AtomizeMainThread(const nsAString& aUTF16String)
+{
+ MOZ_ASSERT(NS_IsMainThread());
+ nsCOMPtr<nsIAtom> retVal;
+ uint32_t hash;
+ AtomTableKey key(aUTF16String.Data(), aUTF16String.Length(), &hash);
+ uint32_t index = hash % RECENTLY_USED_MAIN_THREAD_ATOM_CACHE_SIZE;
+ nsIAtom* atom =
+ sRecentlyUsedMainThreadAtoms[index];
+ if (atom) {
+ uint32_t length = atom->GetLength();
+ if (length == key.mLength &&
+ (memcmp(atom->GetUTF16String(),
+ key.mUTF16String, length * sizeof(char16_t)) == 0)) {
+ retVal = atom;
+ return retVal.forget();
+ }
+ }
+
+ MutexAutoLock lock(*gAtomTableLock);
+ AtomTableEntry* he = static_cast<AtomTableEntry*>(gAtomTable->Add(&key));
+
+ if (he->mAtom) {
+ retVal = he->mAtom;
+ } else {
+ retVal = DynamicAtom::Create(aUTF16String, hash);
+ he->mAtom = retVal;
+ }
+
+ sRecentlyUsedMainThreadAtoms[index] = retVal;
+ return retVal.forget();
+}
+
nsrefcnt
NS_GetNumberOfAtoms(void)
{
diff --git a/xpcom/ds/nsIAtom.idl b/xpcom/ds/nsIAtom.idl
index c02540838..6e8602c42 100644
--- a/xpcom/ds/nsIAtom.idl
+++ b/xpcom/ds/nsIAtom.idl
@@ -120,6 +120,11 @@ extern already_AddRefed<nsIAtom> NS_Atomize(const char16_t* aUTF16String);
extern already_AddRefed<nsIAtom> NS_Atomize(const nsAString& aUTF16String);
/**
+ * An optimized version of the method above for the main thread.
+ */
+extern already_AddRefed<nsIAtom> NS_AtomizeMainThread(const nsAString& aUTF16String);
+
+/**
* Return a count of the total number of atoms currently
* alive in the system.
*/