public AcceptableEntry(PipFingerprintEntry entry)
{
Contract.Requires(entry != null);
Entry = entry;
}
/// <summary>
/// Attempts to store a fingerprint entry; this is a compare-exchange operation, in which <paramref name="previousEntry"/>
/// must match what is currently stored (or must be <c>null</c> if no entry is currently stored).
/// This operation will fail if the previous entry doesn't match, or if the store could not normally proceed.
/// </summary>
public async Task <Possible <CacheEntryPublishResult, Failure> > TryStoreFingerprintEntryAsync(
ContentFingerprint fingerprint,
PipFingerprintEntry entry,
PipFingerprintEntry previousEntry = null,
bool replaceExisting = true,
CacheQueryData cacheQueryData = null)
{
Contract.Assume(entry != null);
Analysis.IgnoreArgument(previousEntry); // See class remarks; replace semantics are broken.
// We have in hand a PipFingerprintEntry which the underlyign m_twoPhaseStore does not understand.
// We will serialize it and store it to the CAS, and that CAS hash will be the stored entry's MetadataHash.
// See symmetric deserialization in TryGetFingerprintEntryAsync.
Possible <ContentHash, Failure> maybeStored = await m_contentCache.TrySerializeAndStoreContent(entry);
if (!maybeStored.Succeeded)
{
return(maybeStored.Failure.Annotate("Failed to store cache-entry metadata to the CAS"));
}
ContentHash metadataHash = maybeStored.Result;
// The metadata (single-phase entry) is stored, so now we can construct an entry that references it.
// From now on, 'twoPhaseEntry' will mean 'the entry we are actually storing in the two-phase store'.
// Meanwhile, like any implementation, we assume that the referenced content (e.g. output files)
// were stored by the caller already.
ContentHash[] twoPhaseReferencedHashes = entry.OutputContentHashes.Select(b => b.ToContentHash()).Where(hash => !hash.IsSpecialValue()).ToArray();
CacheEntry twoPhaseEntry = new CacheEntry(metadataHash, null, ArrayView <ContentHash> .FromArray(twoPhaseReferencedHashes));
StrongContentFingerprint dummyFingerprint = ComputeDummyStrongFingerprint(
m_pathTable,
fingerprint);
var weakFingerprint = new WeakContentFingerprint(fingerprint.Hash);
Possible <CacheEntryPublishResult, Failure> maybePublished = await m_twoPhaseStore.TryPublishCacheEntryAsync(
weakFingerprint : weakFingerprint,
pathSetHash : s_dummyPathSetHash,
strongFingerprint : dummyFingerprint,
entry : twoPhaseEntry,
mode : replaceExisting?CacheEntryPublishMode.CreateNewOrReplaceExisting : CacheEntryPublishMode.CreateNew);
if (cacheQueryData != null)
{
cacheQueryData.WeakContentFingerprint = weakFingerprint;
cacheQueryData.PathSetHash = s_dummyPathSetHash;
cacheQueryData.StrongContentFingerprint = dummyFingerprint;
cacheQueryData.ContentCache = m_contentCache;
}
if (maybePublished.Succeeded)
{
if (maybePublished.Result.Status == CacheEntryPublishStatus.Published ||
(!replaceExisting && maybePublished.Result.Status == CacheEntryPublishStatus.RejectedDueToConflictingEntry))
{
return(maybePublished.Result);
}
else
{
// ISinglePhaseFingerprintStore represents conflicts as failures.
return(new Failure <string>(
"Failed to publish a cache entry; the underlying two-phase store indicated an entry conflict (maybe it does not allow replacement of existing entries)."));
}
}
else
{
return(maybePublished.Failure);
}
}
