void CacheEntry::AsyncOpen(nsICacheEntryOpenCallback* aCallback, uint32_t aFlags)
{
LOG(("CacheEntry::AsyncOpen [this=%p, state=%s, flags=%d, callback=%p]",
this, StateString(mState), aFlags, aCallback));
bool readonly = aFlags & nsICacheStorage::OPEN_READONLY;
bool bypassIfBusy = aFlags & nsICacheStorage::OPEN_BYPASS_IF_BUSY;
bool truncate = aFlags & nsICacheStorage::OPEN_TRUNCATE;
bool priority = aFlags & nsICacheStorage::OPEN_PRIORITY;
bool multithread = aFlags & nsICacheStorage::CHECK_MULTITHREADED;
bool secret = aFlags & nsICacheStorage::OPEN_SECRETLY;
MOZ_ASSERT(!readonly || !truncate, "Bad flags combination");
MOZ_ASSERT(!(truncate && mState > LOADING), "Must not call truncate on already loaded entry");
Callback callback(this, aCallback, readonly, multithread, secret);
if (!Open(callback, truncate, priority, bypassIfBusy)) {
// We get here when the callback wants to bypass cache when it's busy.
LOG((" writing or revalidating, callback wants to bypass cache"));
callback.mNotWanted = true;
InvokeAvailableCallback(callback);
}
}
bool CacheEntry::InvokeCallback(Callback & aCallback)
{
LOG(("CacheEntry::InvokeCallback [this=%p, state=%s, cb=%p]",
this, StateString(mState), aCallback.mCallback.get()));
mLock.AssertCurrentThreadOwns();
// When this entry is doomed we want to notify the callback any time
if (!mIsDoomed) {
// When we are here, the entry must be loaded from disk
MOZ_ASSERT(mState > LOADING);
if (mState == WRITING || mState == REVALIDATING) {
// Prevent invoking other callbacks since one of them is now writing
// or revalidating this entry. No consumers should get this entry
// until metadata are filled with values downloaded from the server
// or the entry revalidated and output stream has been opened.
LOG((" entry is being written/revalidated, callback bypassed"));
return false;
}
// mRecheckAfterWrite flag already set means the callback has already passed
// the onCacheEntryCheck call. Until the current write is not finished this
// callback will be bypassed.
if (!aCallback.mRecheckAfterWrite) {
if (!aCallback.mReadOnly) {
if (mState == EMPTY) {
// Advance to writing state, we expect to invoke the callback and let
// it fill content of this entry. Must set and check the state here
// to prevent more then one
mState = WRITING;
LOG((" advancing to WRITING state"));
}
if (!aCallback.mCallback) {
// We can be given no callback only in case of recreate, it is ok
// to advance to WRITING state since the caller of recreate is expected
// to write this entry now.
return true;
}
}
if (mState == READY) {
// Metadata present, validate the entry
uint32_t checkResult;
{
// mayhemer: TODO check and solve any potential races of concurent OnCacheEntryCheck
mozilla::MutexAutoUnlock unlock(mLock);
nsresult rv = aCallback.mCallback->OnCacheEntryCheck(
this, nullptr, &checkResult);
LOG((" OnCacheEntryCheck: rv=0x%08x, result=%d", rv, checkResult));
if (NS_FAILED(rv))
checkResult = ENTRY_NOT_WANTED;
}
aCallback.mRevalidating = checkResult == ENTRY_NEEDS_REVALIDATION;
switch (checkResult) {
case ENTRY_WANTED:
// Nothing more to do here, the consumer is responsible to handle
// the result of OnCacheEntryCheck it self.
// Proceed to callback...
break;
case RECHECK_AFTER_WRITE_FINISHED:
LOG((" consumer will check on the entry again after write is done"));
// The consumer wants the entry to complete first.
aCallback.mRecheckAfterWrite = true;
break;
case ENTRY_NEEDS_REVALIDATION:
LOG((" will be holding callbacks until entry is revalidated"));
// State is READY now and from that state entry cannot transit to any other
// state then REVALIDATING for which cocurrency is not an issue. Potentially
// no need to lock here.
mState = REVALIDATING;
break;
case ENTRY_NOT_WANTED:
LOG((" consumer not interested in the entry"));
// Do not give this entry to the consumer, it is not interested in us.
aCallback.mNotWanted = true;
break;
}
}
}
}
if (aCallback.mCallback) {
if (!mIsDoomed && aCallback.mRecheckAfterWrite) {
// If we don't have data and the callback wants a complete entry,
// don't invoke now.
bool bypass = !mHasData;
if (!bypass && NS_SUCCEEDED(mFileStatus)) {
int64_t _unused;
bypass = !mFile->DataSize(&_unused);
}
if (bypass) {
LOG((" bypassing, entry data still being written"));
return false;
}
// Entry is complete now, do the check+avail call again
aCallback.mRecheckAfterWrite = false;
return InvokeCallback(aCallback);
}
mozilla::MutexAutoUnlock unlock(mLock);
InvokeAvailableCallback(aCallback);
}
return true;
}
bool CacheEntry::InvokeCallback(nsICacheEntryOpenCallback* aCallback,
bool aReadOnly)
{
LOG(("CacheEntry::InvokeCallback [this=%p, state=%s, cb=%p]",
this, StateString(mState), aCallback));
mLock.AssertCurrentThreadOwns();
bool notWanted = false;
if (!mIsDoomed) {
// When we are here, the entry must be loaded from disk
MOZ_ASSERT(mState > LOADING);
if (mState == WRITING ||
mState == REVALIDATING) {
// Prevent invoking other callbacks since one of them is now writing
// or revalidating this entry. No consumers should get this entry
// until metadata are filled with values downloaded from the server
// or the entry revalidated and output stream has been opened.
LOG((" entry is being written/revalidated, callback bypassed"));
return false;
}
if (!aReadOnly) {
if (mState == EMPTY) {
// Advance to writing state, we expect to invoke the callback and let
// it fill content of this entry. Must set and check the state here
// to prevent more then one
mState = WRITING;
LOG((" advancing to WRITING state"));
}
if (!aCallback) {
// We can be given no callback only in case of recreate, it is ok
// to advance to WRITING state since the caller of recreate is expected
// to write this entry now.
return true;
}
if (mState == READY) {
// Metadata present, validate the entry
uint32_t checkResult;
{
// mayhemer: TODO check and solve any potential races of concurent OnCacheEntryCheck
mozilla::MutexAutoUnlock unlock(mLock);
nsresult rv = aCallback->OnCacheEntryCheck(this, nullptr, &checkResult);
LOG((" OnCacheEntryCheck: rv=0x%08x, result=%d", rv, checkResult));
if (NS_FAILED(rv))
checkResult = ENTRY_WANTED;
}
switch (checkResult) {
case ENTRY_WANTED:
// Nothing more to do here, the consumer is responsible to handle
// the result of OnCacheEntryCheck it self.
// Proceed to callback...
break;
case ENTRY_NEEDS_REVALIDATION:
LOG((" will be holding callbacks until entry is revalidated"));
// State is READY now and from that state entry cannot transit to any other
// state then REVALIDATING for which cocurrency is not an issue. Potentially
// no need to lock here.
mState = REVALIDATING;
break;
case ENTRY_NOT_WANTED:
LOG((" consumer not interested in the entry"));
// Do not give this entry to the consumer, it is not interested in us.
notWanted = true;
break;
}
}
}
}
if (aCallback) {
mozilla::MutexAutoUnlock unlock(mLock);
InvokeAvailableCallback(aCallback, aReadOnly, notWanted);
}
return true;
}
