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Rename replicator to replica

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This commit is contained in:
Ben Johnson
2020-12-29 12:49:23 -07:00
parent 81e99c8035
commit 41448ceb89
4 changed files with 71 additions and 72 deletions
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77
replicator.go
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@@ -15,13 +15,12 @@ import (
"time"
)
// Replicator represents a method for replicating the snapshot & WAL data to
// a remote destination.
type Replicator interface {
// The name of the replicator. Defaults to type if no name specified.
// Replica represents a remote destination to replicate the database & WAL.
type Replica interface {
// The name of the replica. Defaults to type if no name specified.
Name() string
// String identifier for the type of replicator ("file", "s3", etc).
// String identifier for the type of replica ("file", "s3", etc).
Type() string
// Starts replicating in a background goroutine.
@@ -30,7 +29,7 @@ type Replicator interface {
// Stops all replication processing. Blocks until processing stopped.
Stop()
// Returns a list of generation names for the replicator.
// Returns a list of generation names for the replica.
Generations(ctx context.Context) ([]string, error)
// Returns basic information about a generation including the number of
@@ -52,12 +51,12 @@ type Replicator interface {
WALReader(ctx context.Context, generation string, index int) (io.ReadCloser, error)
}
var _ Replicator = (*FileReplicator)(nil)
var _ Replica = (*FileReplica)(nil)
// FileReplicator is a replicator that replicates a DB to a local file path.
type FileReplicator struct {
// FileReplica is a replica that replicates a DB to a local file path.
type FileReplica struct {
db *DB // source database
name string // replicator name, optional
name string // replica name, optional
dst string // destination path
// mu sync.RWMutex
@@ -67,9 +66,9 @@ type FileReplicator struct {
cancel func()
}
// NewFileReplicator returns a new instance of FileReplicator.
func NewFileReplicator(db *DB, name, dst string) *FileReplicator {
return &FileReplicator{
// NewFileReplica returns a new instance of FileReplica.
func NewFileReplica(db *DB, name, dst string) *FileReplica {
return &FileReplica{
db: db,
name: name,
dst: dst,
@@ -77,41 +76,41 @@ func NewFileReplicator(db *DB, name, dst string) *FileReplicator {
}
}
// Name returns the name of the replicator. Returns the type if no name set.
func (r *FileReplicator) Name() string {
// Name returns the name of the replica. Returns the type if no name set.
func (r *FileReplica) Name() string {
if r.name != "" {
return r.name
}
return r.Type()
}
// Type returns the type of replicator.
func (r *FileReplicator) Type() string {
// Type returns the type of replica.
func (r *FileReplica) Type() string {
return "file"
}
// SnapshotDir returns the path to a generation's snapshot directory.
func (r *FileReplicator) SnapshotDir(generation string) string {
func (r *FileReplica) SnapshotDir(generation string) string {
return filepath.Join(r.dst, "generations", generation, "snapshots")
}
// SnapshotPath returns the path to a snapshot file.
func (r *FileReplicator) SnapshotPath(generation string, index int) string {
func (r *FileReplica) SnapshotPath(generation string, index int) string {
return filepath.Join(r.SnapshotDir(generation), fmt.Sprintf("%016x.snapshot.gz", index))
}
// WALDir returns the path to a generation's WAL directory
func (r *FileReplicator) WALDir(generation string) string {
func (r *FileReplica) WALDir(generation string) string {
return filepath.Join(r.dst, "generations", generation, "wal")
}
// WALPath returns the path to a WAL file.
func (r *FileReplicator) WALPath(generation string, index int) string {
func (r *FileReplica) WALPath(generation string, index int) string {
return filepath.Join(r.WALDir(generation), fmt.Sprintf("%016x.wal", index))
}
// Generations returns a list of available generation names.
func (r *FileReplicator) Generations(ctx context.Context) ([]string, error) {
func (r *FileReplica) Generations(ctx context.Context) ([]string, error) {
fis, err := ioutil.ReadDir(filepath.Join(r.dst, "generations"))
if os.IsNotExist(err) {
return nil, nil
@@ -132,7 +131,7 @@ func (r *FileReplicator) Generations(ctx context.Context) ([]string, error) {
}
// GenerationStats returns stats for a generation.
func (r *FileReplicator) GenerationStats(ctx context.Context, generation string) (stats GenerationStats, err error) {
func (r *FileReplica) GenerationStats(ctx context.Context, generation string) (stats GenerationStats, err error) {
// Determine stats for all snapshots.
n, min, max, err := r.snapshotStats(generation)
if err != nil {
@@ -159,7 +158,7 @@ func (r *FileReplicator) GenerationStats(ctx context.Context, generation string)
return stats, nil
}
func (r *FileReplicator) snapshotStats(generation string) (n int, min, max time.Time, err error) {
func (r *FileReplica) snapshotStats(generation string) (n int, min, max time.Time, err error) {
fis, err := ioutil.ReadDir(r.SnapshotDir(generation))
if os.IsNotExist(err) {
return n, min, max, nil
@@ -184,7 +183,7 @@ func (r *FileReplicator) snapshotStats(generation string) (n int, min, max time.
return n, min, max, nil
}
func (r *FileReplicator) walStats(generation string) (n int, min, max time.Time, err error) {
func (r *FileReplica) walStats(generation string) (n int, min, max time.Time, err error) {
fis, err := ioutil.ReadDir(r.WALDir(generation))
if os.IsNotExist(err) {
return n, min, max, nil
@@ -217,7 +216,7 @@ type GenerationStats struct {
}
// Start starts replication for a given generation.
func (r *FileReplicator) Start(ctx context.Context) {
func (r *FileReplica) Start(ctx context.Context) {
// Stop previous replication.
r.Stop()
@@ -230,13 +229,13 @@ func (r *FileReplicator) Start(ctx context.Context) {
}
// Stop cancels any outstanding replication and blocks until finished.
func (r *FileReplicator) Stop() {
func (r *FileReplica) Stop() {
r.cancel()
r.wg.Wait()
}
// monitor runs in a separate goroutine and continuously replicates the DB.
func (r *FileReplicator) monitor(ctx context.Context) {
func (r *FileReplica) monitor(ctx context.Context) {
// Clear old temporary files that my have been left from a crash.
if err := removeTmpFiles(r.dst); err != nil {
log.Printf("%s(%s): cannot remove tmp files: %w", r.db.Path(), r.Name(), err)
@@ -294,9 +293,9 @@ func (r *FileReplicator) monitor(ctx context.Context) {
}
}
// pos returns the position for the replicator for the current generation.
// pos returns the position for the replica for the current generation.
// Returns a zero value if there is no active generation.
func (r *FileReplicator) pos() (pos Pos, err error) {
func (r *FileReplica) pos() (pos Pos, err error) {
// Find the current generation from the DB. Return zero pos if no generation.
generation, err := r.db.CurrentGeneration()
if err != nil {
@@ -346,7 +345,7 @@ func (r *FileReplicator) pos() (pos Pos, err error) {
}
// snapshot copies the entire database to the replica path.
func (r *FileReplicator) snapshot(ctx context.Context, generation string, index int) error {
func (r *FileReplica) snapshot(ctx context.Context, generation string, index int) error {
// Acquire a read lock on the database during snapshot to prevent checkpoints.
tx, err := r.db.db.Begin()
if err != nil {
@@ -371,7 +370,7 @@ func (r *FileReplicator) snapshot(ctx context.Context, generation string, index
}
// snapshotN returns the number of snapshots for a generation.
func (r *FileReplicator) snapshotN(generation string) (int, error) {
func (r *FileReplica) snapshotN(generation string) (int, error) {
fis, err := ioutil.ReadDir(r.SnapshotDir(generation))
if os.IsNotExist(err) {
return 0, nil
@@ -388,7 +387,7 @@ func (r *FileReplicator) snapshotN(generation string) (int, error) {
return n, nil
}
func (r *FileReplicator) sync(ctx context.Context, pos Pos) (_ Pos, err error) {
func (r *FileReplica) sync(ctx context.Context, pos Pos) (_ Pos, err error) {
// Read all WAL files since the last position.
for {
if pos, err = r.syncNext(ctx, pos); err == io.EOF {
@@ -399,7 +398,7 @@ func (r *FileReplicator) sync(ctx context.Context, pos Pos) (_ Pos, err error) {
}
}
func (r *FileReplicator) syncNext(ctx context.Context, pos Pos) (_ Pos, err error) {
func (r *FileReplica) syncNext(ctx context.Context, pos Pos) (_ Pos, err error) {
rd, err := r.db.ShadowWALReader(pos)
if err == io.EOF {
return pos, err
@@ -446,7 +445,7 @@ func (r *FileReplicator) syncNext(ctx context.Context, pos Pos) (_ Pos, err erro
}
// compress gzips all WAL files before the current one.
func (r *FileReplicator) compress(ctx context.Context, generation string) error {
func (r *FileReplica) compress(ctx context.Context, generation string) error {
dir := r.WALDir(generation)
filenames, err := filepath.Glob(filepath.Join(dir, "*.wal"))
if err != nil {
@@ -480,7 +479,7 @@ func (r *FileReplicator) compress(ctx context.Context, generation string) error
// SnapsotIndexAt returns the highest index for a snapshot within a generation
// that occurs before timestamp. If timestamp is zero, returns the latest snapshot.
func (r *FileReplicator) SnapshotIndexAt(ctx context.Context, generation string, timestamp time.Time) (int, error) {
func (r *FileReplica) SnapshotIndexAt(ctx context.Context, generation string, timestamp time.Time) (int, error) {
fis, err := ioutil.ReadDir(r.SnapshotDir(generation))
if os.IsNotExist(err) {
return 0, ErrNoSnapshots
@@ -513,7 +512,7 @@ func (r *FileReplicator) SnapshotIndexAt(ctx context.Context, generation string,
// Returns the highest index for a WAL file that occurs before timestamp.
// If timestamp is zero, returns the highest WAL index.
func (r *FileReplicator) WALIndexAt(ctx context.Context, generation string, timestamp time.Time) (int, error) {
func (r *FileReplica) WALIndexAt(ctx context.Context, generation string, timestamp time.Time) (int, error) {
fis, err := ioutil.ReadDir(r.WALDir(generation))
if os.IsNotExist(err) {
return 0, nil
@@ -544,7 +543,7 @@ func (r *FileReplicator) WALIndexAt(ctx context.Context, generation string, time
// SnapshotReader returns a reader for snapshot data at the given generation/index.
// Returns os.ErrNotExist if no matching index is found.
func (r *FileReplicator) SnapshotReader(ctx context.Context, generation string, index int) (io.ReadCloser, error) {
func (r *FileReplica) SnapshotReader(ctx context.Context, generation string, index int) (io.ReadCloser, error) {
dir := r.SnapshotDir(generation)
fis, err := ioutil.ReadDir(dir)
if err != nil {
@@ -581,7 +580,7 @@ func (r *FileReplicator) SnapshotReader(ctx context.Context, generation string,
// WALReader returns a reader for WAL data at the given index.
// Returns os.ErrNotExist if no matching index is found.
func (r *FileReplicator) WALReader(ctx context.Context, generation string, index int) (io.ReadCloser, error) {
func (r *FileReplica) WALReader(ctx context.Context, generation string, index int) (io.ReadCloser, error) {
filename := r.WALPath(generation, index)
// Attempt to read uncompressed file first.