objstorageprovider

type PreallocatedReadHandle struct {
	// contains filtered or unexported fields
}

type Settings struct {
	Logger base.Logger

	// Local filesystem configuration.
	FS        vfs.FS
	FSDirName string

	// FSDirInitialListing is a listing of FSDirName at the time of calling Open.
	//
	// This is an optional optimization to avoid double listing on Open when the
	// higher layer already has a listing. When nil, we obtain the listing on
	// Open.
	FSDirInitialListing []string

	// Cleaner cleans obsolete files from the local filesystem.
	//
	// The default cleaner uses the DeleteCleaner.
	FSCleaner base.Cleaner

	// NoSyncOnClose decides whether the implementation will enforce a
	// close-time synchronization (e.g., fdatasync() or sync_file_range())
	// on files it writes to. Setting this to true removes the guarantee for a
	// sync on close. Some implementations can still issue a non-blocking sync.
	NoSyncOnClose bool

	// BytesPerSync enables periodic syncing of files in order to smooth out
	// writes to disk. This option does not provide any persistence guarantee, but
	// is used to avoid latency spikes if the OS automatically decides to write
	// out a large chunk of dirty filesystem buffers.
	BytesPerSync int

	// Fields here are set only if the provider is to support remote objects
	// (experimental).
	Remote struct {
		StorageFactory remote.StorageFactory

		// If CreateOnShared is non-zero, sstables are created on remote storage using
		// the CreateOnSharedLocator (when the PreferSharedStorage create option is
		// true).
		CreateOnShared        remote.CreateOnSharedStrategy
		CreateOnSharedLocator remote.Locator

		// CacheSizeBytes is the size of the on-disk block cache for objects
		// on remote storage. If it is 0, no cache is used.
		CacheSizeBytes int64

		// CacheBlockSize is the block size of the cache; if 0, the default of 32KB is used.
		CacheBlockSize int

		// ShardingBlockSize is the size of a shard block. The cache is split into contiguous
		// ShardingBlockSize units. The units are distributed across multiple independent shards
		// of the cache, via a hash(offset) modulo num shards operation. The cache replacement
		// policies operate at the level of shard, not whole cache. This is done to reduce lock
		// contention.
		//
		// If ShardingBlockSize is 0, the default of 1 MB is used.
		ShardingBlockSize int64

		// The number of independent shards the cache leverages. Each shard is the same size,
		// and a hash of filenum & offset map a read to a certain shard. If set to 0,
		// 2*runtime.GOMAXPROCS is used as the shard count.
		CacheShardCount int
	}
}