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194 lines
11 KiB
194 lines
11 KiB
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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#[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"]
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#[doc="and uses fewer mallocs, but loses protection from application bugs"]
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#[doc="like wild pointer writes and other bad updates into the database."]
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#[doc="Incompatible with nested transactions."]
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#[doc="Processes with and without `MDB_WRITEMAP` on the same environment do"]
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#[doc="not cooperate well."]
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const MDB_WRITEMAP = 0x80000,
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#[doc="Open the environment or transaction in read-only mode. No write operations"]
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#[doc="will be allowed. When opening an environment, LMDB will still modify the lock"]
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#[doc="file - except on 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 #mdb_env_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 #mdb_env_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 #mdb_env_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="`MDB_txn` objects instead of to threads. I.e. #mdb_txn_reset() keeps"]
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#[doc="the slot reseved for the #MDB_txn 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 itself. 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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#[doc="Create the named database if it doesn't exist. This option is not"]
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#[doc="allowed in a read-only transaction or a read-only environment."]
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const MDB_CREATE = 0x40000,
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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="Enter the new key/data pair only if it does not"]
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#[doc="already appear in the database. This flag may only be specified"]
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#[doc="if the database was opened with `MDB_DUPSORT`. The function will"]
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#[doc="return `MDB_KEYEXIST` if the key/data pair already appears in the"]
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#[doc="database."]
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const MDB_NODUPDATA = 0x20,
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#[doc="Enter the new key/data pair only if the key"]
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#[doc="does not already appear in the database. The function will return"]
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#[doc="`KeyExist` if the key already appears in the database, even if"]
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#[doc="the database supports duplicates (`MDB_DUPSORT`). The `data`"]
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#[doc="parameter will be set to point to the existing item."]
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const MDB_NOOVERWRITE = 0x10,
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#[doc="Reserve space for data of the given size, but"]
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#[doc="don't copy the given data. Instead, return a pointer to the"]
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#[doc="reserved space, which the caller can fill in later - before"]
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#[doc="the next update operation or the transaction ends. This saves"]
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#[doc="an extra memcpy if the data is being generated later."]
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#[doc="LMDB does nothing else with this memory, the caller is expected"]
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#[doc="to modify all of the space requested."]
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const MDB_RESERVE = 0x10000,
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#[doc="Append the given key/data pair to the end of the"]
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#[doc="database. No key comparisons are performed. This option allows"]
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#[doc="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"]
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#[doc="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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