Factor out BlobStoreWithRandomKeys

src/blobstore/CMakeLists.txt

@@ -1,2 +1,3 @@
+add_subdirectory(interface)
 add_subdirectory(utils)
 add_subdirectory(implementations)

src/blobstore/implementations/inmemory/CMakeLists.txt

@@ -1,3 +1,3 @@
 add_library(blobstore_inmemory InMemoryBlob.cpp InMemoryBlobStore.cpp)
 
-target_link_libraries(blobstore_inmemory blobstore_utils)
+target_link_libraries(blobstore_inmemory blobstore_interface blobstore_utils)

src/blobstore/implementations/inmemory/InMemoryBlobStore.cpp

@@ -12,10 +12,9 @@ namespace blobstore {
 namespace inmemory {
 
 InMemoryBlobStore::InMemoryBlobStore()
- : _blobs(), _generate_key_mutex() {}
+ : _blobs() {}
 
-BlobStore::BlobWithKey InMemoryBlobStore::create(size_t size) {
-  std::string key = _generateKey();
+BlobWithKey InMemoryBlobStore::create(const std::string &key, size_t size) {
   InMemoryBlob blob(size);
   _blobs.insert(make_pair(key, blob));
 
@@ -23,19 +22,8 @@ BlobStore::BlobWithKey InMemoryBlobStore::create(size_t size) {
   return BlobWithKey(key, make_unique<InMemoryBlob>(blob));
 }
 
-string InMemoryBlobStore::_generateKey() {
-  lock_guard<mutex> lock(_generate_key_mutex);
-
-  string key;
-  do {
-    key = _generateRandomKey();
-  } while (_blobs.count(key) > 0);
-
-  return key;
-}
-
-string InMemoryBlobStore::_generateRandomKey() {
-  return RandomKeyGenerator::singleton().create();
+bool InMemoryBlobStore::exists(const std::string &key) {
+  return _blobs.count(key) > 0;
 }
 
 unique_ptr<Blob> InMemoryBlobStore::load(const string &key) {

src/blobstore/implementations/inmemory/InMemoryBlobStore.h

@@ -2,7 +2,7 @@
 #ifndef BLOBSTORE_IMPLEMENTATIONS_INMEMORY_INMEMORYBLOBSTORE_H_
 #define BLOBSTORE_IMPLEMENTATIONS_INMEMORY_INMEMORYBLOBSTORE_H_
 
-#include "blobstore/interface/BlobStore.h"
+#include "blobstore/interface/helpers/BlobStoreWithRandomKeys.h"
 
 #include "fspp/utils/macros.h"
 
@@ -13,19 +13,18 @@ namespace blobstore {
 namespace inmemory {
 class InMemoryBlob;
 
-class InMemoryBlobStore: public BlobStore {
+class InMemoryBlobStore: public BlobStoreWithRandomKeys {
 public:
   InMemoryBlobStore();
 
-  BlobWithKey create(size_t size) override;
+  bool exists(const std::string &key) override;
   std::unique_ptr<Blob> load(const std::string &key) override;
 
-private:
-  std::string _generateKey();
-  std::string _generateRandomKey();
+protected:
+  BlobWithKey create(const std::string &key, size_t size) override;
 
+private:
   std::map<std::string, InMemoryBlob> _blobs;
-  std::mutex _generate_key_mutex;
 
   DISALLOW_COPY_AND_ASSIGN(InMemoryBlobStore);
 };

src/blobstore/implementations/ondisk/CMakeLists.txt

@@ -1,3 +1,3 @@
 add_library(blobstore_ondisk OnDiskBlob.cpp OnDiskBlobStore.cpp FileAlreadyExistsException.cpp)
 
-target_link_libraries(blobstore_ondisk blobstore_utils boost_filesystem boost_system)
+target_link_libraries(blobstore_ondisk blobstore_interface blobstore_utils boost_filesystem boost_system)

src/blobstore/implementations/ondisk/OnDiskBlobStore.cpp

@@ -14,29 +14,18 @@ namespace blobstore {
 namespace ondisk {
 
 OnDiskBlobStore::OnDiskBlobStore(const boost::filesystem::path &rootdir)
- : _rootdir(rootdir), _generate_key_mutex() {}
+ : _rootdir(rootdir) {}
 
-BlobStore::BlobWithKey OnDiskBlobStore::create(size_t size) {
-  std::string key = _generateKey();
+BlobWithKey OnDiskBlobStore::create(const std::string &key, size_t size) {
   auto file_path = _rootdir / key;
   auto blob = OnDiskBlob::CreateOnDisk(file_path, size);
 
-  return BlobStore::BlobWithKey(key, std::move(blob));
+  return BlobWithKey(key, std::move(blob));
 }
 
-string OnDiskBlobStore::_generateKey() {
-  lock_guard<mutex> lock(_generate_key_mutex);
-
-  string key;
-  do {
-    key = _generateRandomKey();
-  } while (bf::exists(_rootdir / key));
-
-  return key;
-}
-
-string OnDiskBlobStore::_generateRandomKey() {
-  return RandomKeyGenerator::singleton().create();
+bool OnDiskBlobStore::exists(const std::string &key) {
+  auto file_path = _rootdir / key;
+  return bf::exists(file_path);
 }
 
 unique_ptr<Blob> OnDiskBlobStore::load(const string &key) {

src/blobstore/implementations/ondisk/OnDiskBlobStore.h

@@ -2,7 +2,7 @@
 #ifndef BLOBSTORE_IMPLEMENTATIONS_ONDISK_ONDISKBLOBSTORE_H_
 #define BLOBSTORE_IMPLEMENTATIONS_ONDISK_ONDISKBLOBSTORE_H_
 
-#include "blobstore/interface/BlobStore.h"
+#include "blobstore/interface/helpers/BlobStoreWithRandomKeys.h"
 
 #include <boost/filesystem.hpp>
 
@@ -13,19 +13,18 @@
 namespace blobstore {
 namespace ondisk {
 
-class OnDiskBlobStore: public BlobStore {
+class OnDiskBlobStore: public BlobStoreWithRandomKeys {
 public:
   OnDiskBlobStore(const boost::filesystem::path &rootdir);
 
-  BlobWithKey create(size_t size) override;
+  bool exists(const std::string &key) override;
   std::unique_ptr<Blob> load(const std::string &key) override;
 
-private:
-  std::string _generateKey();
-  std::string _generateRandomKey();
-  const boost::filesystem::path _rootdir;
+protected:
+  BlobWithKey create(const std::string &key, size_t size) override;
 
-  std::mutex _generate_key_mutex;
+private:
+  const boost::filesystem::path _rootdir;
 
   DISALLOW_COPY_AND_ASSIGN(OnDiskBlobStore);
 };

src/blobstore/interface/BlobStore.h

@@ -6,6 +6,7 @@
 #include <memory>
 
 #include "Blob.h"
+#include "blobstore/utils/BlobWithKey.h"
 
 namespace blobstore {
 
@@ -15,15 +16,9 @@ class BlobStore {
 public:
   virtual ~BlobStore() {}
 
-  struct BlobWithKey {
-    BlobWithKey(const std::string &key_, std::unique_ptr<Blob> &&blob_): key(key_), blob(std::move(blob_)) {}
-
-    std::string key;
-    std::unique_ptr<Blob> blob;
-  };
-
   virtual BlobWithKey create(size_t size) = 0;
   virtual std::unique_ptr<Blob> load(const std::string &key) = 0;
+  virtual bool exists(const std::string &key) = 0;
   //TODO Needed for performance? Or is deleting loaded blobs enough?
   //virtual void remove(const std::string &key) = 0;
 };

src/blobstore/interface/CMakeLists.txt

@@ -0,0 +1 @@
+add_library(blobstore_interface helpers/BlobStoreWithRandomKeys.cpp)

src/blobstore/interface/helpers/BlobStoreWithRandomKeys.cpp

@@ -0,0 +1,32 @@
+#include "BlobStoreWithRandomKeys.h"
+
+#include "blobstore/utils/RandomKeyGenerator.h"
+
+using namespace blobstore;
+
+using std::string;
+using std::lock_guard;
+using std::mutex;
+
+BlobStoreWithRandomKeys::BlobStoreWithRandomKeys()
+  :_generate_key_mutex() {
+}
+
+BlobWithKey BlobStoreWithRandomKeys::create(size_t size) {
+  return create(_generateKey(), size);
+}
+
+string BlobStoreWithRandomKeys::_generateKey() {
+  lock_guard<mutex> lock(_generate_key_mutex);
+
+  string key;
+  do {
+    key = _generateRandomKey();
+  } while (exists(key));
+
+  return key;
+}
+
+string BlobStoreWithRandomKeys::_generateRandomKey() {
+  return RandomKeyGenerator::singleton().create();
+}

src/blobstore/interface/helpers/BlobStoreWithRandomKeys.h

@@ -0,0 +1,33 @@
+#pragma once
+#ifndef FSPP_BLOBSTORE_BLOBSTOREWITHRANDOMKEYS_H_
+#define FSPP_BLOBSTORE_BLOBSTOREWITHRANDOMKEYS_H_
+
+#include <mutex>
+
+#include "blobstore/interface/Blob.h"
+#include "blobstore/interface/BlobStore.h"
+
+namespace blobstore {
+
+class BlobStoreWithRandomKeys: public BlobStore {
+public:
+  BlobStoreWithRandomKeys();
+  virtual ~BlobStoreWithRandomKeys() {}
+
+  BlobWithKey create(size_t size) override;
+
+  virtual std::unique_ptr<Blob> load(const std::string &key) = 0;
+
+protected:
+  virtual BlobWithKey create(const std::string &key, size_t size) = 0;
+
+private:
+  std::string _generateKey();
+  std::string _generateRandomKey();
+
+  std::mutex _generate_key_mutex;
+};
+
+}
+
+#endif

src/blobstore/utils/BlobWithKey.h

@@ -0,0 +1,20 @@
+#pragma once
+#ifndef BLOBSTORE_INTERFACE_BLOBWITHKEY_H_
+#define BLOBSTORE_INTERFACE_BLOBWITHKEY_H_
+
+#include "blobstore/interface/Blob.h"
+
+#include <memory>
+
+namespace blobstore {
+
+struct BlobWithKey {
+  BlobWithKey(const std::string &key_, std::unique_ptr<Blob> &&blob_): key(key_), blob(std::move(blob_)) {}
+
+  std::string key;
+  std::unique_ptr<Blob> blob;
+};
+
+}
+
+#endif