SyncFS: Introduce RemoteSyncOperationResolver for directory operation support

chrome/browser/sync_file_system/remote_sync_operation_resolver.cc

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/sync_file_system/remote_sync_operation_resolver.h"
+
+#include "base/logging.h"
+
+namespace sync_file_system {
+
+namespace {
+
+bool IsValidCombination(const FileChangeList& local_changes,
+                        SyncFileType local_file_type,
+                        bool is_conflicting) {
+  if (local_changes.empty()) {
+    // We never leave directory or non-existing entry in conflicting state, so
+    // if there're no local changes it shouldn't be in conflicting state or
+    // should be a file.
+    return !(is_conflicting && local_file_type != SYNC_FILE_TYPE_FILE);
+  }
+
+  switch (local_file_type) {
+    case SYNC_FILE_TYPE_UNKNOWN:
+      return local_changes.back().IsDelete();
+    case SYNC_FILE_TYPE_FILE:
+    case SYNC_FILE_TYPE_DIRECTORY:
+      return !local_changes.back().IsDelete() &&
+          local_changes.back().file_type() == local_file_type;
+  }
+  return false;
+}
+
+}  // namespace
+
+RemoteSyncOperationType
+RemoteSyncOperationResolver::Resolve(const FileChange& remote_file_change,
+                                     const FileChangeList& local_changes,
+                                     SyncFileType local_file_type,
+                                     bool is_conflicting) {
+  switch (remote_file_change.change()) {
+    case FileChange::FILE_CHANGE_ADD_OR_UPDATE:
+      switch (remote_file_change.file_type()) {
+        case SYNC_FILE_TYPE_FILE:
+          return is_conflicting
+              ? ResolveForAddOrUpdateFileInConflict(local_changes,
+                                                    local_file_type)
+              : ResolveForAddOrUpdateFile(local_changes, local_file_type);
+        case SYNC_FILE_TYPE_DIRECTORY:
+          return is_conflicting
+              ? ResolveForAddDirectoryInConflict(local_changes, local_file_type)
+              : ResolveForAddDirectory(local_changes, local_file_type);
+        case SYNC_FILE_TYPE_UNKNOWN:
+          NOTREACHED();
+          return REMOTE_SYNC_OPERATION_FAIL;
+      }
+      break;
+    case FileChange::FILE_CHANGE_DELETE:
+      switch (remote_file_change.file_type()) {
+        case SYNC_FILE_TYPE_FILE:
+          return is_conflicting
+              ? ResolveForDeleteFileInConflict(local_changes, local_file_type)
+              : ResolveForDeleteFile(local_changes, local_file_type);
+        case SYNC_FILE_TYPE_DIRECTORY:
+          return is_conflicting
+              ? ResolveForDeleteDirectoryInConflict(local_changes,
+                                                    local_file_type)
+              : ResolveForDeleteDirectory(local_changes, local_file_type);
+        case SYNC_FILE_TYPE_UNKNOWN:
+          NOTREACHED();
+          return REMOTE_SYNC_OPERATION_FAIL;
+      }
+      break;
+  }
+  NOTREACHED();
+  return REMOTE_SYNC_OPERATION_FAIL;
+}
+
+RemoteSyncOperationType
+RemoteSyncOperationResolver::ResolveForAddOrUpdateFile(
+    const FileChangeList& local_changes,
+    SyncFileType local_file_type) {
+  // Invalid combination should never happen.
+  if (!IsValidCombination(local_changes, local_file_type, false))
+    return REMOTE_SYNC_OPERATION_FAIL;
+
+  switch (local_file_type) {
+    case SYNC_FILE_TYPE_UNKNOWN:
+      return REMOTE_SYNC_OPERATION_ADD_FILE;
+    case SYNC_FILE_TYPE_FILE:
+      if (local_changes.empty())
+        return REMOTE_SYNC_OPERATION_UPDATE_FILE;
+      return REMOTE_SYNC_OPERATION_CONFLICT;
+    case SYNC_FILE_TYPE_DIRECTORY:
+      // Currently we always prioritize directories over files.
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_LOCAL;
+  }
+  return REMOTE_SYNC_OPERATION_FAIL;
+}
+
+RemoteSyncOperationType
+RemoteSyncOperationResolver::ResolveForAddOrUpdateFileInConflict(
+    const FileChangeList& local_changes,
+    SyncFileType local_file_type) {
+  // Invalid combination should never happen.
+  if (!IsValidCombination(local_changes, local_file_type, true))
+    return REMOTE_SYNC_OPERATION_FAIL;
+
+  switch (local_file_type) {
+    case SYNC_FILE_TYPE_UNKNOWN:
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_REMOTE;
+    case SYNC_FILE_TYPE_FILE:
+      return REMOTE_SYNC_OPERATION_CONFLICT;
+    case SYNC_FILE_TYPE_DIRECTORY:
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_LOCAL;
+  }
+  return REMOTE_SYNC_OPERATION_FAIL;
+}
+
+RemoteSyncOperationType
+RemoteSyncOperationResolver::ResolveForAddDirectory(
+    const FileChangeList& local_changes,
+    SyncFileType local_file_type) {
+  // Invalid combination should never happen.
+  if (!IsValidCombination(local_changes, local_file_type, false))
+    return REMOTE_SYNC_OPERATION_FAIL;
+
+  switch (local_file_type) {
+    case SYNC_FILE_TYPE_UNKNOWN:
+      if (local_changes.empty())
+        return REMOTE_SYNC_OPERATION_ADD_DIRECTORY;
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_REMOTE;
+    case SYNC_FILE_TYPE_FILE:
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_REMOTE;
+    case SYNC_FILE_TYPE_DIRECTORY:
+      return REMOTE_SYNC_OPERATION_NONE;
+  }
+  return REMOTE_SYNC_OPERATION_FAIL;
+}
+
+RemoteSyncOperationType
+RemoteSyncOperationResolver::ResolveForAddDirectoryInConflict(
+    const FileChangeList& local_changes,
+    SyncFileType local_file_type) {
+  // Invalid combination should never happen.
+  if (!IsValidCombination(local_changes, local_file_type, true))
+    return REMOTE_SYNC_OPERATION_FAIL;
+
+  switch (local_file_type) {
+    case SYNC_FILE_TYPE_UNKNOWN:
+    case SYNC_FILE_TYPE_FILE:
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_REMOTE;
+    case SYNC_FILE_TYPE_DIRECTORY:
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_LOCAL;
+  }
+  return REMOTE_SYNC_OPERATION_FAIL;
+}
+
+RemoteSyncOperationType
+RemoteSyncOperationResolver::ResolveForDeleteFile(
+    const FileChangeList& local_changes,
+    SyncFileType local_file_type) {
+  // Invalid combination should never happen.
+  if (!IsValidCombination(local_changes, local_file_type, false))
+    return REMOTE_SYNC_OPERATION_FAIL;
+
+  switch (local_file_type) {
+    case SYNC_FILE_TYPE_UNKNOWN:
+      return REMOTE_SYNC_OPERATION_DELETE_METADATA;
+    case SYNC_FILE_TYPE_FILE:
+      if (local_changes.empty())
+        return REMOTE_SYNC_OPERATION_DELETE_FILE;
+      return REMOTE_SYNC_OPERATION_NONE;
+    case SYNC_FILE_TYPE_DIRECTORY:
+      return REMOTE_SYNC_OPERATION_NONE;
+  }
+  return REMOTE_SYNC_OPERATION_FAIL;
+}
+
+RemoteSyncOperationType
+RemoteSyncOperationResolver::ResolveForDeleteFileInConflict(
+    const FileChangeList& local_changes,
+    SyncFileType local_file_type) {
+  // Invalid combination should never happen.
+  if (!IsValidCombination(local_changes, local_file_type, true))
+    return REMOTE_SYNC_OPERATION_FAIL;
+
+  switch (local_file_type) {
+    case SYNC_FILE_TYPE_UNKNOWN:
+      return REMOTE_SYNC_OPERATION_DELETE_METADATA;
+    case SYNC_FILE_TYPE_FILE:
+    case SYNC_FILE_TYPE_DIRECTORY:
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_LOCAL;
+  }
+  return REMOTE_SYNC_OPERATION_FAIL;
+}
+
+RemoteSyncOperationType
+RemoteSyncOperationResolver::ResolveForDeleteDirectory(
+    const FileChangeList& local_changes,
+    SyncFileType local_file_type) {
+  // Invalid combination should never happen.
+  if (!IsValidCombination(local_changes, local_file_type, false))
+    return REMOTE_SYNC_OPERATION_FAIL;
+
+  switch (local_file_type) {
+    case SYNC_FILE_TYPE_UNKNOWN:
+      return REMOTE_SYNC_OPERATION_NONE;
+    case SYNC_FILE_TYPE_FILE:
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_LOCAL;
+    case SYNC_FILE_TYPE_DIRECTORY:
+      if (local_changes.empty())
+        return REMOTE_SYNC_OPERATION_DELETE_DIRECTORY;
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_LOCAL;
+  }
+  return REMOTE_SYNC_OPERATION_FAIL;
+}
+
+RemoteSyncOperationType
+RemoteSyncOperationResolver::ResolveForDeleteDirectoryInConflict(
+    const FileChangeList& local_changes,
+    SyncFileType local_file_type) {
+  // Invalid combination should never happen.
+  if (!IsValidCombination(local_changes, local_file_type, true))
+    return REMOTE_SYNC_OPERATION_FAIL;
+
+  switch (local_file_type) {
+    case SYNC_FILE_TYPE_UNKNOWN:
+      return REMOTE_SYNC_OPERATION_DELETE_METADATA;
+    case SYNC_FILE_TYPE_FILE:
+    case SYNC_FILE_TYPE_DIRECTORY:
+      return REMOTE_SYNC_OPERATION_RESOLVE_TO_LOCAL;
+  }
+  return REMOTE_SYNC_OPERATION_FAIL;
+}
+
+}  // namespace sync_file_system