X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/a06f90e1dcaa2c4ce2613e066e7c1348ec129ba8..e59b78c774872e33b9c69acc196989a0f565bdf4:/services/keepstore/volume.go diff --git a/services/keepstore/volume.go b/services/keepstore/volume.go index 64fea34bfe..6bce05bec0 100644 --- a/services/keepstore/volume.go +++ b/services/keepstore/volume.go @@ -1,57 +1,349 @@ -// A Volume is an interface representing a Keep back-end storage unit: -// for example, a single mounted disk, a RAID array, an Amazon S3 volume, -// etc. +// Copyright (C) The Arvados Authors. All rights reserved. +// +// SPDX-License-Identifier: AGPL-3.0 package main import ( + "context" + "crypto/rand" + "fmt" "io" + "math/big" "sync/atomic" "time" + + "git.curoverse.com/arvados.git/sdk/go/arvados" ) +type BlockWriter interface { + // WriteBlock reads all data from r, writes it to a backing + // store as "loc", and returns the number of bytes written. + WriteBlock(ctx context.Context, loc string, r io.Reader) error +} + +type BlockReader interface { + // ReadBlock retrieves data previously stored as "loc" and + // writes it to w. + ReadBlock(ctx context.Context, loc string, w io.Writer) error +} + +// A Volume is an interface representing a Keep back-end storage unit: +// for example, a single mounted disk, a RAID array, an Amazon S3 volume, +// etc. type Volume interface { - // Get a block. IFF the returned error is nil, the caller must - // put the returned slice back into the buffer pool when it's - // finished with it. - Get(loc string) ([]byte, error) - Put(loc string, block []byte) error + // Volume type as specified in config file. Examples: "S3", + // "Directory". + Type() string + + // Do whatever private setup tasks and configuration checks + // are needed. Return non-nil if the volume is unusable (e.g., + // invalid config). + Start() error + + // Get a block: copy the block data into buf, and return the + // number of bytes copied. + // + // loc is guaranteed to consist of 32 or more lowercase hex + // digits. + // + // Get should not verify the integrity of the data: it should + // just return whatever was found in its backing + // store. (Integrity checking is the caller's responsibility.) + // + // If an error is encountered that prevents it from + // retrieving the data, that error should be returned so the + // caller can log (and send to the client) a more useful + // message. + // + // If the error is "not found", and there's no particular + // reason to expect the block to be found (other than that a + // caller is asking for it), the returned error should satisfy + // os.IsNotExist(err): this is a normal condition and will not + // be logged as an error (except that a 404 will appear in the + // access log if the block is not found on any other volumes + // either). + // + // If the data in the backing store is bigger than len(buf), + // then Get is permitted to return an error without reading + // any of the data. + // + // len(buf) will not exceed BlockSize. + Get(ctx context.Context, loc string, buf []byte) (int, error) + + // Compare the given data with the stored data (i.e., what Get + // would return). If equal, return nil. If not, return + // CollisionError or DiskHashError (depending on whether the + // data on disk matches the expected hash), or whatever error + // was encountered opening/reading the stored data. + Compare(ctx context.Context, loc string, data []byte) error + + // Put writes a block to an underlying storage device. + // + // loc is as described in Get. + // + // len(block) is guaranteed to be between 0 and BlockSize. + // + // If a block is already stored under the same name (loc) with + // different content, Put must either overwrite the existing + // data with the new data or return a non-nil error. When + // overwriting existing data, it must never leave the storage + // device in an inconsistent state: a subsequent call to Get + // must return either the entire old block, the entire new + // block, or an error. (An implementation that cannot peform + // atomic updates must leave the old data alone and return an + // error.) + // + // Put also sets the timestamp for the given locator to the + // current time. + // + // Put must return a non-nil error unless it can guarantee + // that the entire block has been written and flushed to + // persistent storage, and that its timestamp is current. Of + // course, this guarantee is only as good as the underlying + // storage device, but it is Put's responsibility to at least + // get whatever guarantee is offered by the storage device. + // + // Put should not verify that loc==hash(block): this is the + // caller's responsibility. + Put(ctx context.Context, loc string, block []byte) error + + // Touch sets the timestamp for the given locator to the + // current time. + // + // loc is as described in Get. + // + // If invoked at time t0, Touch must guarantee that a + // subsequent call to Mtime will return a timestamp no older + // than {t0 minus one second}. For example, if Touch is called + // at 2015-07-07T01:23:45.67890123Z, it is acceptable for a + // subsequent Mtime to return any of the following: + // + // - 2015-07-07T01:23:45.00000000Z + // - 2015-07-07T01:23:45.67890123Z + // - 2015-07-07T01:23:46.67890123Z + // - 2015-07-08T00:00:00.00000000Z + // + // It is not acceptable for a subsequente Mtime to return + // either of the following: + // + // - 2015-07-07T00:00:00.00000000Z -- ERROR + // - 2015-07-07T01:23:44.00000000Z -- ERROR + // + // Touch must return a non-nil error if the timestamp cannot + // be updated. Touch(loc string) error + + // Mtime returns the stored timestamp for the given locator. + // + // loc is as described in Get. + // + // Mtime must return a non-nil error if the given block is not + // found or the timestamp could not be retrieved. Mtime(loc string) (time.Time, error) + + // IndexTo writes a complete list of locators with the given + // prefix for which Get() can retrieve data. + // + // prefix consists of zero or more lowercase hexadecimal + // digits. + // + // Each locator must be written to the given writer using the + // following format: + // + // loc "+" size " " timestamp "\n" + // + // where: + // + // - size is the number of bytes of content, given as a + // decimal number with one or more digits + // + // - timestamp is the timestamp stored for the locator, + // given as a decimal number of seconds after January 1, + // 1970 UTC. + // + // IndexTo must not write any other data to writer: for + // example, it must not write any blank lines. + // + // If an error makes it impossible to provide a complete + // index, IndexTo must return a non-nil error. It is + // acceptable to return a non-nil error after writing a + // partial index to writer. + // + // The resulting index is not expected to be sorted in any + // particular order. IndexTo(prefix string, writer io.Writer) error - Delete(loc string) error + + // Trash moves the block data from the underlying storage + // device to trash area. The block then stays in trash for + // -trash-lifetime interval before it is actually deleted. + // + // loc is as described in Get. + // + // If the timestamp for the given locator is newer than + // BlobSignatureTTL, Trash must not trash the data. + // + // If a Trash operation overlaps with any Touch or Put + // operations on the same locator, the implementation must + // ensure one of the following outcomes: + // + // - Touch and Put return a non-nil error, or + // - Trash does not trash the block, or + // - Both of the above. + // + // If it is possible for the storage device to be accessed by + // a different process or host, the synchronization mechanism + // should also guard against races with other processes and + // hosts. If such a mechanism is not available, there must be + // a mechanism for detecting unsafe configurations, alerting + // the operator, and aborting or falling back to a read-only + // state. In other words, running multiple keepstore processes + // with the same underlying storage device must either work + // reliably or fail outright. + // + // Corollary: A successful Touch or Put guarantees a block + // will not be trashed for at least BlobSignatureTTL + // seconds. + Trash(loc string) error + + // Untrash moves block from trash back into store + Untrash(loc string) error + + // Status returns a *VolumeStatus representing the current + // in-use and available storage capacity and an + // implementation-specific volume identifier (e.g., "mount + // point" for a UnixVolume). Status() *VolumeStatus + + // String returns an identifying label for this volume, + // suitable for including in log messages. It should contain + // enough information to uniquely identify the underlying + // storage device, but should not contain any credentials or + // secrets. String() string + + // Writable returns false if all future Put, Mtime, and Delete + // calls are expected to fail. + // + // If the volume is only temporarily unwritable -- or if Put + // will fail because it is full, but Mtime or Delete can + // succeed -- then Writable should return false. Writable() bool + + // Replication returns the storage redundancy of the + // underlying device. It will be passed on to clients in + // responses to PUT requests. + Replication() int + + // EmptyTrash looks for trashed blocks that exceeded TrashLifetime + // and deletes them from the volume. + EmptyTrash() + + // Return a globally unique ID of the underlying storage + // device if possible, otherwise "". + DeviceID() string + + // Get the storage classes associated with this volume + GetStorageClasses() []string +} + +// A VolumeWithExamples provides example configs to display in the +// -help message. +type VolumeWithExamples interface { + Volume + Examples() []Volume } // A VolumeManager tells callers which volumes can read, which volumes // can write, and on which volume the next write should be attempted. type VolumeManager interface { + // Mounts returns all mounts (volume attachments). + Mounts() []*VolumeMount + + // Lookup returns the volume under the given mount + // UUID. Returns nil if the mount does not exist. If + // write==true, returns nil if the volume is not writable. + Lookup(uuid string, write bool) Volume + // AllReadable returns all volumes. AllReadable() []Volume + // AllWritable returns all volumes that aren't known to be in // a read-only state. (There is no guarantee that a write to // one will succeed, though.) AllWritable() []Volume + // NextWritable returns the volume where the next new block // should be written. A VolumeManager can select a volume in // order to distribute activity across spindles, fill up disks // with more free space, etc. NextWritable() Volume + + // VolumeStats returns the ioStats used for tracking stats for + // the given Volume. + VolumeStats(Volume) *ioStats + // Close shuts down the volume manager cleanly. Close() } +// A VolumeMount is an attachment of a Volume to a VolumeManager. +type VolumeMount struct { + arvados.KeepMount + volume Volume +} + +// Generate a UUID the way API server would for a "KeepVolumeMount" +// object. +func (*VolumeMount) generateUUID() string { + var max big.Int + _, ok := max.SetString("zzzzzzzzzzzzzzz", 36) + if !ok { + panic("big.Int parse failed") + } + r, err := rand.Int(rand.Reader, &max) + if err != nil { + panic(err) + } + return fmt.Sprintf("zzzzz-ivpuk-%015s", r.Text(36)) +} + +// RRVolumeManager is a round-robin VolumeManager: the Nth call to +// NextWritable returns the (N % len(writables))th writable Volume +// (where writables are all Volumes v where v.Writable()==true). type RRVolumeManager struct { + mounts []*VolumeMount + mountMap map[string]*VolumeMount readables []Volume writables []Volume counter uint32 + iostats map[Volume]*ioStats } +// MakeRRVolumeManager initializes RRVolumeManager func MakeRRVolumeManager(volumes []Volume) *RRVolumeManager { - vm := &RRVolumeManager{} + vm := &RRVolumeManager{ + iostats: make(map[Volume]*ioStats), + } + vm.mountMap = make(map[string]*VolumeMount) for _, v := range volumes { + sc := v.GetStorageClasses() + if len(sc) == 0 { + sc = []string{"default"} + } + mnt := &VolumeMount{ + KeepMount: arvados.KeepMount{ + UUID: (*VolumeMount)(nil).generateUUID(), + DeviceID: v.DeviceID(), + ReadOnly: !v.Writable(), + Replication: v.Replication(), + StorageClasses: sc, + }, + volume: v, + } + vm.iostats[v] = &ioStats{} + vm.mounts = append(vm.mounts, mnt) + vm.mountMap[mnt.UUID] = mnt vm.readables = append(vm.readables, v) if v.Writable() { vm.writables = append(vm.writables, v) @@ -60,14 +352,29 @@ func MakeRRVolumeManager(volumes []Volume) *RRVolumeManager { return vm } +func (vm *RRVolumeManager) Mounts() []*VolumeMount { + return vm.mounts +} + +func (vm *RRVolumeManager) Lookup(uuid string, needWrite bool) Volume { + if mnt, ok := vm.mountMap[uuid]; ok && (!needWrite || !mnt.ReadOnly) { + return mnt.volume + } else { + return nil + } +} + +// AllReadable returns an array of all readable volumes func (vm *RRVolumeManager) AllReadable() []Volume { return vm.readables } +// AllWritable returns an array of all writable volumes func (vm *RRVolumeManager) AllWritable() []Volume { return vm.writables } +// NextWritable returns the next writable func (vm *RRVolumeManager) NextWritable() Volume { if len(vm.writables) == 0 { return nil @@ -76,5 +383,35 @@ func (vm *RRVolumeManager) NextWritable() Volume { return vm.writables[i%uint32(len(vm.writables))] } +// VolumeStats returns an ioStats for the given volume. +func (vm *RRVolumeManager) VolumeStats(v Volume) *ioStats { + return vm.iostats[v] +} + +// Close the RRVolumeManager func (vm *RRVolumeManager) Close() { } + +// VolumeStatus describes the current condition of a volume +type VolumeStatus struct { + MountPoint string + DeviceNum uint64 + BytesFree uint64 + BytesUsed uint64 +} + +// ioStats tracks I/O statistics for a volume or server +type ioStats struct { + Errors uint64 + Ops uint64 + CompareOps uint64 + GetOps uint64 + PutOps uint64 + TouchOps uint64 + InBytes uint64 + OutBytes uint64 +} + +type InternalStatser interface { + InternalStats() interface{} +}