Dan Burkert
10 years ago
parent
b1c1bb5b0b
commit
c745961037
@ -0,0 +1,183 @@ |
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use libc::c_uint; |
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bitflags! { |
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#[doc="Environment Options"] |
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#[deriving(Show)] |
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flags EnvironmentFlags: c_uint { |
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|
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#[doc="Use a fixed address for the mmap region. This flag must be specified"] |
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#[doc="when creating the environment, and is stored persistently in the environment."] |
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#[doc="If successful, the memory map will always reside at the same virtual address"] |
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#[doc="and pointers used to reference data items in the database will be constant"] |
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#[doc="across multiple invocations. This option may not always work, depending on"] |
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#[doc="how the operating system has allocated memory to shared libraries and other uses."] |
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#[doc="The feature is highly experimental."] |
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const MDB_FIXEDMAP = 0x01, |
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#[doc="By default, LMDB creates its environment in a directory whose"] |
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#[doc="pathname is given in `path`, and creates its data and lock files"] |
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#[doc="under that directory. With this option, `path` is used as-is for"] |
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#[doc="the database main data file. The database lock file is the `path`"] |
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#[doc="with `-lock` appended."] |
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const MDB_NOSUBDIR = 0x4000, |
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#[doc="Use a writeable memory map unless `MDB_RDONLY` is set. This is faster and uses"] |
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#[doc="fewer mallocs, but loses protection from application bugs like wild pointer writes"] |
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#[doc="and other bad updates into the database. Incompatible with nested transactions."] |
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#[doc="Processes with and without `MDB_WRITEMAP` on the same environment do not cooperate"] |
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#[doc="well."] |
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const MDB_WRITEMAP = 0x80000, |
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#[doc="Open the environment in read-only mode. No write operations will be allowed."] |
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#[doc="When opening an environment, LMDB will still modify the lock file - except on"] |
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#[doc="read-only filesystems, where LMDB does not use locks."] |
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const MDB_RDONLY = 0x20000, |
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#[doc="Flush system buffers to disk only once per transaction, omit the"] |
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#[doc="metadata flush. Defer that until the system flushes files to disk,"] |
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#[doc="or next non-`MDB_RDONLY` commit or #mdb_env_sync(). This optimization"] |
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#[doc="maintains database integrity, but a system crash may undo the last"] |
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#[doc="committed transaction. I.e. it preserves the ACI (atomicity,"] |
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#[doc="consistency, isolation) but not D (durability) database property."] |
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#[doc="\n\nThis flag may be changed at any time using `Environment::set_flags`."] |
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const MDB_NOMETASYNC = 0x40000, |
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#[doc="Don't flush system buffers to disk when committing a transaction."] |
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#[doc="This optimization means a system crash can corrupt the database or"] |
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#[doc="lose the last transactions if buffers are not yet flushed to disk."] |
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#[doc="The risk is governed by how often the system flushes dirty buffers"] |
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#[doc="to disk and how often `Environment::sync` is called. However, if the"] |
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#[doc="filesystem preserves write order and the `MDB_WRITEMAP` flag is not"] |
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#[doc="used, transactions exhibit ACI (atomicity, consistency, isolation)"] |
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#[doc="properties and only lose D (durability). I.e. database integrity"] |
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#[doc="is maintained, but a system crash may undo the final transactions."] |
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#[doc="Note that (`MDB_NOSYNC | MDB_WRITEMAP`) leaves the system with no"] |
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#[doc="hint for when to write transactions to disk, unless `Environment::sync`"] |
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#[doc="is called. (`MDB_MAPASYNC | MDB_WRITEMAP`) may be preferable."] |
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#[doc="\n\nThis flag may be changed at any time using `Environment::set_flags`."] |
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const MDB_NOSYNC = 0x10000, |
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#[doc="When using `MDB_WRITEMAP`, use asynchronous flushes to disk."] |
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#[doc="As with `MDB_NOSYNC`, a system crash can then corrupt the"] |
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#[doc="database or lose the last transactions. Calling `Environment::sync`"] |
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#[doc="ensures on-disk database integrity until next commit."] |
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#[doc="\n\nThis flag may be changed at any time using `Environment::set_flags`."] |
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const MDB_MAPASYNC = 0x100000, |
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#[doc="Don't use Thread-Local Storage. Tie reader locktable slots to"] |
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#[doc="transaction objects instead of to threads. I.e. `RoTransaction::reset` keeps"] |
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#[doc="the slot reseved for the transaction object. A thread may use parallel"] |
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#[doc="read-only transactions. A read-only transaction may span threads if"] |
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#[doc="the user synchronizes its use. Applications that multiplex many"] |
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#[doc="user threads over individual OS threads need this option. Such an"] |
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#[doc="application must also serialize the write transactions in an OS"] |
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#[doc="thread, since LMDB's write locking is unaware of the user threads."] |
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const MDB_NOTLS = 0x200000, |
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#[doc="Don't do any locking. If concurrent access is anticipated, the"] |
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#[doc="caller must manage all concurrency themself. For proper operation"] |
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#[doc="the caller must enforce single-writer semantics, and must ensure"] |
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#[doc="that no readers are using old transactions while a writer is"] |
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#[doc="active. The simplest approach is to use an exclusive lock so that"] |
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#[doc="no readers may be active at all when a writer begins."] |
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const MDB_NOLOCK = 0x400000, |
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#[doc="Turn off readahead. Most operating systems perform readahead on"] |
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#[doc="read requests by default. This option turns it off if the OS"] |
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#[doc="supports it. Turning it off may help random read performance"] |
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#[doc="when the DB is larger than RAM and system RAM is full."] |
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#[doc="The option is not implemented on Windows."] |
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const MDB_NORDAHEAD = 0x800000, |
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#[doc="Don't initialize malloc'd memory before writing to unused spaces"] |
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#[doc="in the data file. By default, memory for pages written to the data"] |
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#[doc="file is obtained using malloc. While these pages may be reused in"] |
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#[doc="subsequent transactions, freshly malloc'd pages will be initialized"] |
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#[doc="to zeroes before use. This avoids persisting leftover data from other"] |
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#[doc="code (that used the heap and subsequently freed the memory) into the"] |
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#[doc="data file. Note that many other system libraries may allocate"] |
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#[doc="and free memory from the heap for arbitrary uses. E.g., stdio may"] |
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#[doc="use the heap for file I/O buffers. This initialization step has a"] |
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#[doc="modest performance cost so some applications may want to disable"] |
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#[doc="it using this flag. This option can be a problem for applications"] |
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#[doc="which handle sensitive data like passwords, and it makes memory"] |
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#[doc="checkers like Valgrind noisy. This flag is not needed with `MDB_WRITEMAP`,"] |
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#[doc="which writes directly to the mmap instead of using malloc for pages. The"] |
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#[doc="initialization is also skipped if `MDB_RESERVE` is used; the"] |
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#[doc="caller is expected to overwrite all of the memory that was"] |
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#[doc="reserved in that case."] |
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#[doc="\n\nThis flag may be changed at any time using `Environment::set_flags`."] |
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const MDB_NOMEMINIT = 0x1000000, |
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} |
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} |
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bitflags! { |
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#[doc="Database Options"] |
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#[deriving(Show)] |
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flags DatabaseFlags: c_uint { |
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#[doc="Keys are strings to be compared in reverse order, from the end"] |
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#[doc="of the strings to the beginning. By default, Keys are treated as strings and"] |
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#[doc="compared from beginning to end."] |
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const MDB_REVERSEKEY = 0x02, |
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#[doc="Duplicate keys may be used in the database. (Or, from another perspective,"] |
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#[doc="keys may have multiple data items, stored in sorted order.) By default"] |
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#[doc="keys must be unique and may have only a single data item."] |
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const MDB_DUPSORT = 0x04, |
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#[doc="Keys are binary integers in native byte order. Setting this option"] |
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#[doc="requires all keys to be the same size, typically sizeof(int)"] |
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#[doc="or sizeof(size_t)."] |
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const MDB_INTEGERKEY = 0x08, |
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#[doc="This flag may only be used in combination with `MDB_DUPSORT`. This option"] |
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#[doc="tells the library that the data items for this database are all the same"] |
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#[doc="size, which allows further optimizations in storage and retrieval. When"] |
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#[doc="all data items are the same size, the `MDB_GET_MULTIPLE` and `MDB_NEXT_MULTIPLE`"] |
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#[doc="cursor operations may be used to retrieve multiple items at once."] |
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const MDB_DUPFIXED = 0x10, |
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#[doc="This option specifies that duplicate data items are also integers, and"] |
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#[doc="should be sorted as such."] |
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const MDB_INTEGERDUP = 0x20, |
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#[doc="This option specifies that duplicate data items should be compared as"] |
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#[doc="strings in reverse order."] |
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const MDB_REVERSEDUP = 0x40, |
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} |
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} |
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bitflags! { |
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#[doc="Write Options"] |
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#[deriving(Show)] |
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flags WriteFlags: c_uint { |
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#[doc="Insert the new item only if the key does not already appear in the database."] |
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#[doc="The function will return `LmdbError::KeyExist` if the key already appears in the"] |
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#[doc="database, even if the database supports duplicates (`MDB_DUPSORT`)."] |
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const MDB_NOOVERWRITE = 0x10, |
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#[doc="Insert the new item only if it does not already appear in the database."] |
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#[doc="This flag may only be specified if the database was opened with `MDB_DUPSORT`."] |
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#[doc="The function will return `LmdbError::KeyExist` if the item already appears in the"] |
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#[doc="database."] |
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const MDB_NODUPDATA = 0x20, |
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#[doc="For `Cursor::put`. Replace the item at the current cursor position."] |
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#[doc="The key parameter must match the current position. If using"] |
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#[doc="sorted duplicates (`MDB_DUPSORT`) the data item must still sort into the"] |
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#[doc="same position. This is intended to be used when the new data is the same"] |
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#[doc="size as the old. Otherwise it will simply perform a delete of the old"] |
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#[doc="record followed by an insert."] |
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const MDB_CURRENT = 0x40, |
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#[doc="Append the given item to the end of the database. No key comparisons are performed."] |
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#[doc="This option allows fast bulk loading when keys are already known to be in the"] |
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#[doc="correct order. Loading unsorted keys with this flag will cause data corruption."] |
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const MDB_APPEND = 0x20000, |
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#[doc="Same as `MDB_APPEND`, but for sorted dup data."] |
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const MDB_APPENDDUP = 0x40000, |
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} |
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} |
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