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authorMax Kellermann <max@duempel.org>2014-02-08 15:37:02 +0100
committerMax Kellermann <max@duempel.org>2014-02-09 10:47:29 +0100
commit59ce67e2e55098c8cbe1707e8a32900128345315 (patch)
tree695cb868309c0f055b775605c213ea36399c679f /src
parent2182209a8ac1ed2f0c80893ecac4d81fcab18e18 (diff)
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CompositeStorage: new Storage implementation
This is the backend for the upcoming "mount" command.
Diffstat (limited to 'src')
-rw-r--r--src/storage/CompositeStorage.cxx344
-rw-r--r--src/storage/CompositeStorage.hxx123
2 files changed, 467 insertions, 0 deletions
diff --git a/src/storage/CompositeStorage.cxx b/src/storage/CompositeStorage.cxx
new file mode 100644
index 000000000..e090bd63c
--- /dev/null
+++ b/src/storage/CompositeStorage.cxx
@@ -0,0 +1,344 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "CompositeStorage.hxx"
+#include "FileInfo.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+
+#include <set>
+
+static constexpr Domain composite_domain("composite");
+
+/**
+ * Combines the directory entries of another #StorageDirectoryReader
+ * instance and the virtual directory entries.
+ */
+class CompositeDirectoryReader final : public StorageDirectoryReader {
+ StorageDirectoryReader *other;
+
+ std::set<std::string> names;
+ std::set<std::string>::const_iterator current, next;
+
+public:
+ template<typename M>
+ CompositeDirectoryReader(StorageDirectoryReader *_other,
+ const M &map)
+ :other(_other) {
+ for (const auto &i : map)
+ names.insert(i.first);
+ next = names.begin();
+ }
+
+ virtual ~CompositeDirectoryReader() {
+ delete other;
+ }
+
+ /* virtual methods from class StorageDirectoryReader */
+ virtual const char *Read() override;
+ virtual bool GetInfo(bool follow, FileInfo &info,
+ Error &error) override;
+};
+
+const char *
+CompositeDirectoryReader::Read()
+{
+ if (other != nullptr) {
+ const char *name = other->Read();
+ if (name != nullptr) {
+ names.erase(name);
+ return name;
+ }
+
+ delete other;
+ other = nullptr;
+ }
+
+ if (next == names.end())
+ return nullptr;
+
+ current = next++;
+ return current->c_str();
+}
+
+bool
+CompositeDirectoryReader::GetInfo(bool follow, FileInfo &info,
+ Error &error)
+{
+ if (other != nullptr)
+ return other->GetInfo(follow, info, error);
+
+ assert(current != names.end());
+
+ info.type = FileInfo::Type::DIRECTORY;
+ info.mtime = 0;
+ info.device = 0;
+ info.inode = 0;
+ return true;
+}
+
+static std::string
+NextSegment(const char *&uri_r)
+{
+ const char *uri = uri_r;
+ const char *slash = strchr(uri, '/');
+ if (slash == nullptr) {
+ uri_r += strlen(uri);
+ return std::string(uri);
+ } else {
+ uri_r = slash + 1;
+ return std::string(uri, slash);
+ }
+}
+
+CompositeStorage::Directory::~Directory()
+{
+ delete storage;
+}
+
+const CompositeStorage::Directory *
+CompositeStorage::Directory::Find(const char *uri) const
+{
+ const Directory *directory = this;
+ while (*uri != 0) {
+ const std::string name = NextSegment(uri);
+ auto i = directory->children.find(name);
+ if (i == directory->children.end())
+ return nullptr;
+
+ directory = &i->second;
+ }
+
+ return directory;
+}
+
+CompositeStorage::Directory &
+CompositeStorage::Directory::Make(const char *uri)
+{
+ Directory *directory = this;
+ while (*uri != 0) {
+ const std::string name = NextSegment(uri);
+#if defined(__clang__) || GCC_CHECK_VERSION(4,8)
+ auto i = directory->children.emplace(std::move(name),
+ Directory());
+#else
+ auto i = directory->children.insert(std::make_pair(std::move(name),
+ Directory()));
+#endif
+ directory = &i.first->second;
+ }
+
+ return *directory;
+}
+
+bool
+CompositeStorage::Directory::Unmount()
+{
+ if (storage == nullptr)
+ return false;
+
+ delete storage;
+ storage = nullptr;
+ return true;
+}
+
+bool
+CompositeStorage::Directory::Unmount(const char *uri)
+{
+ const std::string name = NextSegment(uri);
+
+ auto i = children.find(name);
+ if (i == children.end() || !i->second.Unmount())
+ return false;
+
+ if (i->second.IsEmpty())
+ children.erase(i);
+
+ return true;
+
+}
+
+bool
+CompositeStorage::Directory::MapToRelativeUTF8(std::string &buffer,
+ const char *uri) const
+{
+ if (storage != nullptr) {
+ const char *result = storage->MapToRelativeUTF8(uri);
+ if (result != nullptr) {
+ buffer = result;
+ return true;
+ }
+ }
+
+ for (const auto &i : children) {
+ if (i.second.MapToRelativeUTF8(buffer, uri)) {
+ buffer.insert(buffer.begin(), '/');
+ buffer.insert(buffer.begin(),
+ i.first.begin(), i.first.end());
+ return true;
+ }
+ }
+
+ return false;
+}
+
+CompositeStorage::CompositeStorage()
+{
+}
+
+CompositeStorage::~CompositeStorage()
+{
+}
+
+void
+CompositeStorage::Mount(const char *uri, Storage *storage)
+{
+ const ScopeLock protect(mutex);
+
+ Directory &directory = root.Make(uri);
+ if (directory.storage != nullptr)
+ delete directory.storage;
+ directory.storage = storage;
+}
+
+bool
+CompositeStorage::Unmount(const char *uri)
+{
+ const ScopeLock protect(mutex);
+
+ return root.Unmount(uri);
+}
+
+CompositeStorage::FindResult
+CompositeStorage::FindStorage(const char *uri) const
+{
+ FindResult result{&root, uri};
+
+ const Directory *directory = &root;
+ while (*uri != 0) {
+ const std::string name = NextSegment(uri);
+
+ auto i = directory->children.find(name);
+ if (i == directory->children.end())
+ break;
+
+ directory = &i->second;
+ if (directory->storage != nullptr)
+ result = FindResult{directory, uri};
+ }
+
+ return result;
+}
+
+CompositeStorage::FindResult
+CompositeStorage::FindStorage(const char *uri, Error &error) const
+{
+ auto result = FindStorage(uri);
+ if (result.directory == nullptr)
+ error.Set(composite_domain, "No such directory");
+ return result;
+}
+
+bool
+CompositeStorage::GetInfo(const char *uri, bool follow, FileInfo &info,
+ Error &error)
+{
+ const ScopeLock protect(mutex);
+
+ auto f = FindStorage(uri, error);
+ if (f.directory->storage != nullptr &&
+ f.directory->storage->GetInfo(f.uri, follow, info, error))
+ return true;
+
+ const Directory *directory = f.directory->Find(f.uri);
+ if (directory != nullptr) {
+ error.Clear();
+ info.type = FileInfo::Type::DIRECTORY;
+ info.mtime = 0;
+ info.device = 0;
+ info.inode = 0;
+ return true;
+ }
+
+ return false;
+}
+
+StorageDirectoryReader *
+CompositeStorage::OpenDirectory(const char *uri,
+ Error &error)
+{
+ const ScopeLock protect(mutex);
+
+ auto f = FindStorage(uri, error);
+ const Directory *directory = f.directory->Find(f.uri);
+ if (directory == nullptr || directory->children.empty()) {
+ /* no virtual directories here */
+
+ if (f.directory->storage == nullptr)
+ return nullptr;
+
+ return f.directory->storage->OpenDirectory(f.uri, error);
+ }
+
+ StorageDirectoryReader *other =
+ f.directory->storage->OpenDirectory(f.uri, IgnoreError());
+ return new CompositeDirectoryReader(other, directory->children);
+}
+
+std::string
+CompositeStorage::MapUTF8(const char *uri) const
+{
+ const ScopeLock protect(mutex);
+
+ auto f = FindStorage(uri);
+ if (f.directory->storage == nullptr)
+ return std::string();
+
+ return f.directory->storage->MapUTF8(f.uri);
+}
+
+AllocatedPath
+CompositeStorage::MapFS(const char *uri) const
+{
+ const ScopeLock protect(mutex);
+
+ auto f = FindStorage(uri);
+ if (f.directory->storage == nullptr)
+ return AllocatedPath::Null();
+
+ return f.directory->storage->MapFS(f.uri);
+}
+
+const char *
+CompositeStorage::MapToRelativeUTF8(const char *uri) const
+{
+ const ScopeLock protect(mutex);
+
+ if (root.storage != nullptr) {
+ const char *result = root.storage->MapToRelativeUTF8(uri);
+ if (result != nullptr)
+ return result;
+ }
+
+ if (!root.MapToRelativeUTF8(relative_buffer, uri))
+ return nullptr;
+
+ return relative_buffer.c_str();
+}
diff --git a/src/storage/CompositeStorage.hxx b/src/storage/CompositeStorage.hxx
new file mode 100644
index 000000000..696ffff61
--- /dev/null
+++ b/src/storage/CompositeStorage.hxx
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_COMPOSITE_STORAGE_HXX
+#define MPD_COMPOSITE_STORAGE_HXX
+
+#include "check.h"
+#include "StorageInterface.hxx"
+#include "thread/Mutex.hxx"
+#include "Compiler.h"
+
+#include <string>
+#include <map>
+
+class Error;
+class Storage;
+
+/**
+ * A #Storage implementation that combines multiple other #Storage
+ * instances in one virtual tree. It is used to "mount" new #Storage
+ * instances into the storage tree.
+ *
+ * This class is thread-safe: mounts may be added and removed at any
+ * time in any thread.
+ */
+class CompositeStorage final : public Storage {
+ /**
+ * A node in the virtual directory tree.
+ */
+ struct Directory {
+ /**
+ * The #Storage mounted n this virtual directory. All
+ * "leaf" Directory instances must have a #Storage.
+ * Other Directory instances may have one, and child
+ * mounts will be "mixed" in.
+ */
+ Storage *storage;
+
+ std::map<std::string, Directory> children;
+
+ Directory():storage(nullptr) {}
+ ~Directory();
+
+ gcc_pure
+ bool IsEmpty() const {
+ return storage == nullptr && children.empty();
+ }
+
+ gcc_pure
+ const Directory *Find(const char *uri) const;
+
+ Directory &Make(const char *uri);
+
+ bool Unmount();
+ bool Unmount(const char *uri);
+
+ gcc_pure
+ bool MapToRelativeUTF8(std::string &buffer,
+ const char *uri) const;
+ };
+
+ struct FindResult {
+ const Directory *directory;
+ const char *uri;
+ };
+
+ /**
+ * Protects the virtual #Directory tree.
+ *
+ * TODO: use readers-writer lock
+ */
+ mutable Mutex mutex;
+
+ Directory root;
+
+ mutable std::string relative_buffer;
+
+public:
+ CompositeStorage();
+ virtual ~CompositeStorage();
+
+ void Mount(const char *uri, Storage *storage);
+ bool Unmount(const char *uri);
+
+ /* virtual methods from class Storage */
+ virtual bool GetInfo(const char *uri, bool follow, FileInfo &info,
+ Error &error) override;
+
+ virtual StorageDirectoryReader *OpenDirectory(const char *uri,
+ Error &error) override;
+
+ virtual std::string MapUTF8(const char *uri) const override;
+
+ virtual AllocatedPath MapFS(const char *uri) const override;
+
+ virtual const char *MapToRelativeUTF8(const char *uri) const override;
+
+private:
+ gcc_pure
+ FindResult FindStorage(const char *uri) const;
+ FindResult FindStorage(const char *uri, Error &error) const;
+
+ const char *MapToRelativeUTF8(const Directory &directory,
+ const char *uri) const;
+};
+
+#endif