[CAS] Add UnifiedOnDiskCache and OnDiskCAS

llvm/include/llvm/CAS/ActionCache.h

@@ -75,6 +75,9 @@ class ActionCache {
                    CanBeDistributed);
   }
 
+  /// Validate the ActionCache contents.
+  virtual Error validate() const = 0;
+
   virtual ~ActionCache() = default;
 
 protected:
@@ -97,6 +100,9 @@ class ActionCache {
 /// Create an action cache in memory.
 std::unique_ptr<ActionCache> createInMemoryActionCache();
 
+/// Create an action cache on disk.
+Expected<std::unique_ptr<ActionCache>> createOnDiskActionCache(StringRef Path);
+
 } // end namespace llvm::cas
 
 #endif // LLVM_CAS_ACTIONCACHE_H

llvm/include/llvm/CAS/BuiltinUnifiedCASDatabases.h

@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CAS_BUILTINUNIFIEDCASDATABASES_H
+#define LLVM_CAS_BUILTINUNIFIEDCASDATABASES_H
+
+#include "llvm/Support/Error.h"
+
+namespace llvm::cas {
+
+class ActionCache;
+class ObjectStore;
+
+/// Create on-disk \c ObjectStore and \c ActionCache instances based on
+/// \c ondisk::UnifiedOnDiskCache, with built-in hashing.
+Expected<std::pair<std::unique_ptr<ObjectStore>, std::unique_ptr<ActionCache>>>
+createOnDiskUnifiedCASDatabases(StringRef Path);
+
+/// Represents the result of validating the contents using
+/// \c validateOnDiskUnifiedCASDatabasesIfNeeded.
+///
+/// Note: invalid results are handled as an \c Error.
+enum class ValidationResult {
+  /// The data is already valid.
+  Valid,
+  /// The data was invalid, but was recovered.
+  Recovered,
+  /// Validation was skipped, as it was not needed.
+  Skipped,
+};
+
+/// Validate the data in \p Path, if needed to ensure correctness.
+///
+/// \param Path directory for the on-disk database.
+/// \param CheckHash Whether to validate hashes match the data.
+/// \param AllowRecovery Whether to automatically recover from invalid data by
+/// marking the files for garbage collection.
+/// \param ForceValidation Whether to force validation to occur even if it
+/// should not be necessary.
+/// \param LLVMCasBinaryPath If provided, validation is performed out-of-process
+/// using the given \c llvm-cas executable which protects against crashes
+/// during validation. Otherwise validation is performed in-process.
+///
+/// \returns \c Valid if the data is already valid, \c Recovered if data
+/// was invalid but has been cleared, \c Skipped if validation is not needed,
+/// or an \c Error if validation cannot be performed or if the data is left
+/// in an invalid state because \p AllowRecovery is false.
+Expected<ValidationResult> validateOnDiskUnifiedCASDatabasesIfNeeded(
+    StringRef Path, bool CheckHash, bool AllowRecovery, bool ForceValidation,
+    std::optional<StringRef> LLVMCasBinaryPath);
+
+} // namespace llvm::cas
+
+#endif // LLVM_CAS_BUILTINUNIFIEDCASDATABASES_H

llvm/include/llvm/CAS/ObjectStore.h

@@ -5,6 +5,11 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the declaration of the ObjectStore class.
+///
+//===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CAS_OBJECTSTORE_H
 #define LLVM_CAS_OBJECTSTORE_H
@@ -111,7 +116,10 @@ class ObjectStore {
   virtual Expected<bool> isMaterialized(ObjectRef Ref) const = 0;
 
   /// Validate the underlying object referred by CASID.
-  virtual Error validate(const CASID &ID) = 0;
+  virtual Error validateObject(const CASID &ID) = 0;
+
+  /// Validate the entire ObjectStore.
+  virtual Error validate(bool CheckHash) const = 0;
 
 protected:
   /// Load the object referenced by \p Ref.
@@ -215,9 +223,39 @@ class ObjectStore {
     return Data.size();
   }
 
+  /// Set the size for limiting growth of on-disk storage. This has an effect
+  /// for when the instance is closed.
+  ///
+  /// Implementations may leave this unimplemented.
+  virtual Error setSizeLimit(std::optional<uint64_t> SizeLimit) {
+    return Error::success();
+  }
+
+  /// \returns the storage size of the on-disk CAS data.
+  ///
+  /// Implementations that don't have an implementation for this should return
+  /// \p std::nullopt.
+  virtual Expected<std::optional<uint64_t>> getStorageSize() const {
+    return std::nullopt;
+  }
+
+  /// Prune local storage to reduce its size according to the desired size
+  /// limit. Pruning can happen concurrently with other operations.
+  ///
+  /// Implementations may leave this unimplemented.
+  virtual Error pruneStorageData() { return Error::success(); }
+
   /// Validate the whole node tree.
   Error validateTree(ObjectRef Ref);
 
+  /// Import object from another CAS. This will import the full tree from the
+  /// other CAS.
+  Expected<ObjectRef> importObject(ObjectStore &Upstream, ObjectRef Other);
+
+  /// Print the ObjectStore internals for debugging purpose.
+  virtual void print(raw_ostream &) const {}
+  void dump() const;
+
   /// Get CASContext
   const CASContext &getContext() const { return Context; }
 
@@ -290,8 +328,15 @@ class ObjectProxy {
   ObjectHandle H;
 };
 
+/// Create an in memory CAS.
 std::unique_ptr<ObjectStore> createInMemoryCAS();
 
+/// \returns true if \c LLVM_ENABLE_ONDISK_CAS configuration was enabled.
+bool isOnDiskCASEnabled();
+
+/// Create a persistent on-disk path at \p Path.
+Expected<std::unique_ptr<ObjectStore>> createOnDiskCAS(const Twine &Path);
+
 } // namespace cas
 } // namespace llvm
 

llvm/include/llvm/CAS/OnDiskGraphDB.h

@@ -340,13 +340,16 @@ class OnDiskGraphDB {
   /// \param HashByteSize Size for the object digest hash bytes.
   /// \param UpstreamDB Optional on-disk store to be used for faulting-in nodes
   /// if they don't exist in the primary store. The upstream store is only used
-  /// for reading nodes, new nodes are only written to the primary store.
+  /// for reading nodes, new nodes are only written to the primary store. User
+  /// need to make sure \p UpstreamDB outlives current instance of
+  /// OnDiskGraphDB and the common usage is to have an \p UnifiedOnDiskCache to
+  /// manage both.
   /// \param Policy If \p UpstreamDB is provided, controls how nodes are copied
   /// to primary store. This is recorded at creation time and subsequent opens
   /// need to pass the same policy otherwise the \p open will fail.
   static Expected<std::unique_ptr<OnDiskGraphDB>>
   open(StringRef Path, StringRef HashName, unsigned HashByteSize,
-       std::unique_ptr<OnDiskGraphDB> UpstreamDB = nullptr,
+       OnDiskGraphDB *UpstreamDB = nullptr,
        FaultInPolicy Policy = FaultInPolicy::FullTree);
 
   ~OnDiskGraphDB();
@@ -438,8 +441,7 @@ class OnDiskGraphDB {
 
   // Private constructor.
   OnDiskGraphDB(StringRef RootPath, OnDiskTrieRawHashMap Index,
-                OnDiskDataAllocator DataPool,
-                std::unique_ptr<OnDiskGraphDB> UpstreamDB,
+                OnDiskDataAllocator DataPool, OnDiskGraphDB *UpstreamDB,
                 FaultInPolicy Policy);
 
   /// Mapping from hash to object reference.
@@ -459,7 +461,7 @@ class OnDiskGraphDB {
   std::string RootPath;
 
   /// Optional on-disk store to be used for faulting-in nodes.
-  std::unique_ptr<OnDiskGraphDB> UpstreamDB;
+  OnDiskGraphDB *UpstreamDB = nullptr;
 
   /// The policy used to fault in data from upstream.
   FaultInPolicy FIPolicy;

llvm/include/llvm/CAS/OnDiskKeyValueDB.h

@@ -19,6 +19,8 @@
 
 namespace llvm::cas::ondisk {
 
+class UnifiedOnDiskCache;
+
 /// An on-disk key-value data store with the following properties:
 /// * Keys are fixed length binary hashes with expected normal distribution.
 /// * Values are buffers of the same size, specified at creation time.
@@ -59,9 +61,13 @@ class OnDiskKeyValueDB {
   /// \param KeySize Size for the key hash bytes.
   /// \param ValueName Identifier name for the values.
   /// \param ValueSize Size for the value bytes.
+  /// \param UnifiedCache An optional UnifiedOnDiskCache that manages the size
+  /// and lifetime of the CAS instance and it must owns current initializing
+  /// KeyValueDB after initialized.
   static Expected<std::unique_ptr<OnDiskKeyValueDB>>
   open(StringRef Path, StringRef HashName, unsigned KeySize,
-       StringRef ValueName, size_t ValueSize);
+       StringRef ValueName, size_t ValueSize,
+       UnifiedOnDiskCache *UnifiedCache = nullptr);
 
   using CheckValueT =
       function_ref<Error(FileOffset Offset, ArrayRef<char> Data)>;
@@ -70,11 +76,14 @@ class OnDiskKeyValueDB {
   Error validate(CheckValueT CheckValue) const;
 
 private:
-  OnDiskKeyValueDB(size_t ValueSize, OnDiskTrieRawHashMap Cache)
-      : ValueSize(ValueSize), Cache(std::move(Cache)) {}
+  OnDiskKeyValueDB(size_t ValueSize, OnDiskTrieRawHashMap Cache,
+                   UnifiedOnDiskCache *UnifiedCache)
+      : ValueSize(ValueSize), Cache(std::move(Cache)),
+        UnifiedCache(UnifiedCache) {}
 
   const size_t ValueSize;
   OnDiskTrieRawHashMap Cache;
+  UnifiedOnDiskCache *UnifiedCache = nullptr;
 };
 
 } // namespace llvm::cas::ondisk