Class RocksDBBackend
Defined in File rocksdb_backend.hpp
Inheritance Relationships
Base Type
public gkfs::metadata::MetadataBackend< RocksDBBackend >(Template Class MetadataBackend)
Class Documentation
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class gkfs::metadata::RocksDBBackend : public gkfs::metadata::MetadataBackend<RocksDBBackend>
Called when the daemon is started: Connects to the KV store
- Param path
where KV store data is stored
Public Functions
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explicit RocksDBBackend(const std::string &path)
Called when the daemon is started: Connects to the KV store
- Parameters
path – where KV store data is stored
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virtual ~RocksDBBackend()
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void optimize_database_impl()
Used for setting KV store settings
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std::string get_impl(const std::string &key) const
Gets a KV store value for a key
- Parameters
key –
- Throws
DBException – on failure, NotFoundException if entry doesn’t exist
- Returns
value
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void put_impl(const std::string &key, const std::string &val)
Puts an entry into the KV store
- Parameters
key –
val –
- Throws
DBException – on failure
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void put_no_exist_impl(const std::string &key, const std::string &val)
Puts an entry into the KV store if it doesn’t exist. This function does not use a mutex.
- Parameters
key –
val –
- Throws
DBException – on failure, ExistException if entry already exists
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void remove_impl(const std::string &key)
Removes an entry from the KV store
- Parameters
key –
- Throws
DBException – on failure, NotFoundException if entry doesn’t exist
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bool exists_impl(const std::string &key)
checks for existence of an entry
- Parameters
key –
- Throws
DBException – on failure
- Returns
true if exists
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void update_impl(const std::string &old_key, const std::string &new_key, const std::string &val)
Updates a metadentry atomically and also allows to change keys
- Parameters
old_key –
new_key –
val –
- Throws
DBException – on failure, NotFoundException if entry doesn’t exist
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off_t increase_size_impl(const std::string &key, size_t io_size, off_t offset, bool append)
Updates the size on the metadata Operation. E.g., called before a write() call
Updates the size on the metadata Operation. E.g., called before a write() call
A special case represents the append operation. Since multiple processes could want to append a file in parallel, the corresponding offsets where the write operation starts, needs to be reserved. This is an expensive operation as we need to force a RocksDB Merge operation to receive the starting offset for this write request.
- Parameters
key –
io_size –
offset –
append –
key –
io_size –
offset –
append –
- Returns
offset where the write operation should start. This is only used when append is set
- Returns
offset where the write operation should start. This is only used when append is set
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void decrease_size_impl(const std::string &key, size_t size)
Decreases the size on the metadata Operation E.g., called before a truncate() call
- Parameters
key –
size –
- Throws
DBException – on failure
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std::vector<std::pair<std::string, bool>> get_dirents_impl(const std::string &dir) const
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std::vector<std::tuple<std::string, bool, size_t, time_t>> get_dirents_extended_impl(const std::string &dir) const
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void iterate_all_impl() const
Code example for iterating all entries in KV store. This is for debug only as it is too expensive
Public Static Functions
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static inline void throw_status_excpt(const rdb::Status &s)
Exception wrapper on Status object. Throws NotFoundException if s.IsNotFound(), general DBException otherwise
- Parameters
RocksDB – status
- Throws