public async Task <Possible <FullCacheRecordWithDeterminism, Failure> > AddOrGetAsync(WeakFingerprintHash weak, CasHash casElement, Hash hashElement, CasEntries hashes, UrgencyHint urgencyHint, Guid activityId)
{
Contract.Requires(!IsClosed);
Contract.Requires(hashes.IsValid);
Contract.Assert(!IsReadOnly);
using (var counter = m_counters.AddOrGetCounter())
{
using (var eventing = new AddOrGetActivity(BasicFilesystemCache.EventSource, activityId, this))
{
eventing.Start(weak, casElement, hashElement, hashes, urgencyHint);
counter.SetEntriesCount(hashes.Count); // The size of what we are adding (effectively)
// We check the Cas entries if we are strict
if (StrictMetadataCasCoupling)
{
// Check that the content is valid.
if (!m_pinnedToCas.ContainsKey(casElement))
{
counter.Failed();
return(eventing.StopFailure(new UnpinnedCasEntryFailure(CacheId, casElement)));
}
foreach (CasHash hash in hashes)
{
if (!m_pinnedToCas.ContainsKey(hash))
{
counter.Failed();
return(eventing.StopFailure(new UnpinnedCasEntryFailure(CacheId, hash)));
}
}
}
StrongFingerprint strong = new StrongFingerprint(weak, casElement, hashElement, CacheId);
// Assume we accepted the Add and there is nothing to return
FullCacheRecord result = null;
string strongFingerprintName = m_cache.GetStrongFingerprintFilename(strong);
try
{
using (FileStream file = await m_cache.ContendedOpenStreamAsync(strongFingerprintName, FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
// The compiler thinks that it is not assigned down below at the end
// even though it would be set by the writeEntries being true in that case
CasEntries oldCasEntries = hashes;
// Assume we will write our new enties to the file.
bool writeEntries = true;
// If there is some data in the file already, we need to try to read it.
if (file.Length > 0)
{
var possibleOldCasEntries = await m_cache.ReadCacheEntryAsync(file);
// Only if it was formatted correctly do we continue to check if
// we should replace it.
if (possibleOldCasEntries.Succeeded)
{
oldCasEntries = possibleOldCasEntries.Result;
writeEntries = false;
// We can only replace if both or neither is SinglePhaseNonDeterministic
if (oldCasEntries.Determinism.IsSinglePhaseNonDeterministic != hashes.Determinism.IsSinglePhaseNonDeterministic)
{
counter.Failed();
return(eventing.StopFailure(new SinglePhaseMixingFailure(CacheId)));
}
// Should we replace?
if (hashes.Determinism.IsSinglePhaseNonDeterministic ||
(!oldCasEntries.Determinism.IsDeterministicTool &&
(hashes.Determinism.IsDeterministic && !oldCasEntries.Determinism.Equals(hashes.Determinism))))
{
// We are replacing due to determinism
counter.Det();
writeEntries = true;
}
else if (HasMissingContent(oldCasEntries))
{
counter.Repair();
writeEntries = true;
}
else if (oldCasEntries.Determinism.IsDeterministicTool && hashes.Determinism.IsDeterministicTool && !oldCasEntries.Equals(hashes))
{
// We have a non-deterministic tool!
counter.Failed();
return(eventing.StopFailure(new NotDeterministicFailure(CacheId, new FullCacheRecord(strong, oldCasEntries), new FullCacheRecord(strong, hashes))));
}
}
}
// Are we going to write the entries?
if (writeEntries)
{
// We are writing so the old entries don't count
oldCasEntries = hashes;
// Write from the front
file.SetLength(0);
await m_cache.WriteCacheEntryAsync(file, hashes);
}
else
{
counter.Dup();
}
// If what is in the cache is different than what we are
// asking to add, build a FullCacheRecord to return what
// is in the cache.
if (!oldCasEntries.Equals(hashes))
{
counter.Get();
result = new FullCacheRecord(strong, oldCasEntries);
}
}
}
catch (Exception e)
{
counter.Failed();
return(eventing.StopFailure(new StrongFingerprintAccessFailure(m_cache.CacheId, strong, e)));
}
AddSessionRecord(strong);
if (result != null)
{
return
(eventing.Returns(
new FullCacheRecordWithDeterminism(
new FullCacheRecord(
result.StrongFingerprint,
result.CasEntries.GetModifiedCasEntriesWithDeterminism(
m_cache.IsAuthoritative,
m_cache.CacheGuid,
CacheDeterminism.NeverExpires)))));
}
else
{
return(eventing.Returns(new FullCacheRecordWithDeterminism(hashes.GetFinalDeterminism(m_cache.IsAuthoritative, m_cache.CacheGuid, DateTime.UtcNow.Add(m_cache.TimeToLive)))));
}
}
}
}
