Remove old rate-{controller,limiter} code

This code was not actively being used and the mechanisms were
fragile. See #7 for the proposed direction for pacing user writes vs
flushes.

commit.go

@@ -10,8 +10,6 @@ import (
 	"sync"
 	"sync/atomic"
 	"unsafe"
-
-	"github.com/petermattis/pebble/internal/rate"
 )
 
 type commitQueueNode struct {
@@ -121,8 +119,6 @@ type commitEnv struct {
 	// The visible sequence number at which reads should be performed. Ratcheted
 	// upwards atomically as batches are applied to the memtable.
 	visibleSeqNum *uint64
-	// Controller for measuring and limiting the commit rate.
-	controller *controller
 
 	// Apply the batch to the specified memtable. Called concurrently.
 	apply func(b *Batch, mem *memTable) error
@@ -223,9 +219,6 @@ func newCommitPipeline(env commitEnv) *commitPipeline {
 	p := &commitPipeline{
 		env: env,
 	}
-	if p.env.controller == nil {
-		p.env.controller = newController(rate.NewLimiter(rate.Inf, 0))
-	}
 	p.cond.L = p.env.mu
 	p.pending.init()
 	p.syncer.cond.L = &p.syncer.Mutex
@@ -363,8 +356,6 @@ func (p *commitPipeline) prepare(b *Batch, writeWAL, syncWAL bool) (*memTable, e
 	}
 	b.commit.Add(count)
 
-	// p.env.controller.WaitN(len(b.data))
-
 	p.env.mu.Lock()
 
 	// Enqueue the batch in the pending queue. Note that while the pending queue

compaction.go

@@ -527,7 +527,6 @@ func (d *DB) writeLevel0Table(
 	if err != nil {
 		return fileMetadata{}, err
 	}
-	file = newRateLimitedFile(file, d.flushController)
 	tw = sstable.NewWriter(file, d.opts, d.opts.Level(0))
 
 	var count int

db.go

@@ -137,16 +137,6 @@ type DB struct {
 	largeBatchThreshold int
 	optionsFileNum      uint64
 
-	// Rate limiter for how much bandwidth to allow for commits, compactions, and
-	// flushes.
-	//
-	// TODO(peter): Add a controller module that balances the limits so that
-	// commits cannot happen faster than flushes and the backlog of compaction
-	// work does not grow too large.
-	commitController  *controller
-	compactController *controller
-	flushController   *controller
-
 	// TODO(peter): describe exactly what this mutex protects. So far: every
 	// field in the struct.
 	mu struct {

open.go

@@ -14,7 +14,6 @@ import (
 
 	"github.com/petermattis/pebble/db"
 	"github.com/petermattis/pebble/internal/arenaskl"
-	"github.com/petermattis/pebble/internal/rate"
 	"github.com/petermattis/pebble/internal/record"
 	"github.com/petermattis/pebble/storage"
 )
@@ -55,20 +54,14 @@ func createDB(dirname string, opts *db.Options) (retErr error) {
 
 // Open opens a LevelDB whose files live in the given directory.
 func Open(dirname string, opts *db.Options) (*DB, error) {
-	const defaultRateLimit = rate.Limit(50 << 20) // 50 MB/sec
-	const defaultBurst = 1 << 20                  // 1 MB
-
 	opts = opts.EnsureDefaults()
 	d := &DB{
-		dirname:           dirname,
-		opts:              opts,
-		cmp:               opts.Comparer.Compare,
-		equal:             opts.Comparer.Equal,
-		merge:             opts.Merger.Merge,
-		abbreviatedKey:    opts.Comparer.AbbreviatedKey,
-		commitController:  newController(rate.NewLimiter(defaultRateLimit, defaultBurst)),
-		compactController: newController(rate.NewLimiter(defaultRateLimit, defaultBurst)),
-		flushController:   newController(rate.NewLimiter(rate.Inf, defaultBurst)),
+		dirname:        dirname,
+		opts:           opts,
+		cmp:            opts.Comparer.Compare,
+		equal:          opts.Comparer.Equal,
+		merge:          opts.Merger.Merge,
+		abbreviatedKey: opts.Comparer.AbbreviatedKey,
 	}
 	if d.equal == nil {
 		d.equal = bytes.Equal
@@ -83,7 +76,6 @@ func Open(dirname string, opts *db.Options) (*DB, error) {
 		mu:            &d.mu.Mutex,
 		logSeqNum:     &d.mu.versions.logSeqNum,
 		visibleSeqNum: &d.mu.versions.visibleSeqNum,
-		controller:    d.commitController,
 		apply:         d.commitApply,
 		sync:          d.commitSync,
 		write:         d.commitWrite,