Remove serialize_reads package

Will be replaced by go-fuse's new SyncRead flag.

More info: https://github.com/hanwen/go-fuse/issues/395
SyncRead commit: https://github.com/hanwen/go-fuse/commit/15a8bb029a4e1a51e10043c370970596b1fbb737

3 files changed, 1 insertions, 161 deletions

diff --git a/internal/fusefrontend/file.go b/internal/fusefrontend/file.go
index 9481abf..6f33a60 100644
--- a/internal/fusefrontend/file.go
+++ b/internal/fusefrontend/file.go
@@ -20,7 +20,6 @@ import (
 	"github.com/rfjakob/gocryptfs/v2/internal/contentenc"
 	"github.com/rfjakob/gocryptfs/v2/internal/inomap"
 	"github.com/rfjakob/gocryptfs/v2/internal/openfiletable"
-	"github.com/rfjakob/gocryptfs/v2/internal/serialize_reads"
 	"github.com/rfjakob/gocryptfs/v2/internal/stupidgcm"
 	"github.com/rfjakob/gocryptfs/v2/internal/syscallcompat"
 	"github.com/rfjakob/gocryptfs/v2/internal/tlog"
@@ -252,13 +251,7 @@ func (f *File) Read(ctx context.Context, buf []byte, off int64) (resultData fuse
 	defer f.fileTableEntry.ContentLock.RUnlock()
 
 	tlog.Debug.Printf("ino%d: FUSE Read: offset=%d length=%d", f.qIno.Ino, off, len(buf))
-	if f.rootNode.args.SerializeReads {
-		serialize_reads.Wait(off, len(buf))
-	}
 	out, errno := f.doRead(buf[:0], uint64(off), uint64(len(buf)))
-	if f.rootNode.args.SerializeReads {
-		serialize_reads.Done()
-	}
 	if errno != 0 {
 		return nil, errno
 	}
@@ -389,6 +382,7 @@ func (f *File) Write(ctx context.Context, data []byte, off int64) (uint32, sysca
 	// But if the write directly follows an earlier write, it cannot create a
 	// hole, and we can save one Stat() call.
 	if !f.isConsecutiveWrite(off) {
+		fmt.Printf("isConsecutiveWrite=false, off=%d\n", off)
 		errno := f.writePadHole(off)
 		if errno != 0 {
 			return 0, errno
diff --git a/internal/fusefrontend/root_node.go b/internal/fusefrontend/root_node.go
index 34b084b..7d37520 100644
--- a/internal/fusefrontend/root_node.go
+++ b/internal/fusefrontend/root_node.go
@@ -11,7 +11,6 @@ import (
 	"github.com/rfjakob/gocryptfs/v2/internal/contentenc"
 	"github.com/rfjakob/gocryptfs/v2/internal/inomap"
 	"github.com/rfjakob/gocryptfs/v2/internal/nametransform"
-	"github.com/rfjakob/gocryptfs/v2/internal/serialize_reads"
 	"github.com/rfjakob/gocryptfs/v2/internal/syscallcompat"
 	"github.com/rfjakob/gocryptfs/v2/internal/tlog"
 )
@@ -63,9 +62,6 @@ type RootNode struct {
 }
 
 func NewRootNode(args Args, c *contentenc.ContentEnc, n *nametransform.NameTransform) *RootNode {
-	if args.SerializeReads {
-		serialize_reads.InitSerializer()
-	}
 	if len(args.Exclude) > 0 {
 		tlog.Warn.Printf("Forward mode does not support -exclude")
 	}
diff --git a/internal/serialize_reads/sr.go b/internal/serialize_reads/sr.go
deleted file mode 100644
index 88115f9..0000000
--- a/internal/serialize_reads/sr.go
+++ /dev/null
@@ -1,150 +0,0 @@
-package serialize_reads
-
-import (
-	"log"
-	"sync"
-	"time"
-
-	"github.com/rfjakob/gocryptfs/v2/internal/tlog"
-)
-
-// serializerState is used by the Wait and Done functions
-type serializerState struct {
-	// we get submissions through the "input" channel
-	input chan *submission
-	// q = Queue
-	q []*submission
-	// wg is used to wait for the read to complete before unblocking the next
-	wg sync.WaitGroup
-}
-
-// Wait places the caller into a queue and blocks
-func Wait(offset int64, size int) {
-	serializer.wait(offset, size)
-}
-
-// Done signals that the read operation has finished
-func Done() {
-	serializer.wg.Done()
-}
-
-type submission struct {
-	// "ch" is closed by "eventLoop" once it wants to unblock the caller
-	ch chan struct{}
-	// submissions are prioritized by offset (lowest offset gets unblocked first)
-	offset int64
-	// size will be used in the future to detect consecutive read requests. These
-	// can be unblocked immediately.
-	size int
-}
-
-func (sr *serializerState) wait(offset int64, size int) {
-	ch := make(chan struct{})
-	sb := &submission{
-		ch:     ch,
-		offset: offset,
-		size:   size,
-	}
-	// Send our submission
-	sr.input <- sb
-	// Wait till we get unblocked
-	<-ch
-}
-
-// push returns true if the queue is full after the element has been stored.
-// It panics if it did not have space to store the element.
-func (sr *serializerState) push(sb *submission) (full bool) {
-	free := 0
-	stored := false
-	for i, v := range sr.q {
-		if v != nil {
-			continue
-		}
-		if !stored {
-			sr.q[i] = sb
-			stored = true
-			continue
-		}
-		free++
-	}
-	if !stored {
-		// This should never happen because eventLoop checks if the queue got full
-		log.Panic("BUG: unhandled queue overflow")
-	}
-	if free == 0 {
-		return true
-	}
-	return false
-}
-
-// pop the submission with the lowest offset off the queue
-func (sr *serializerState) pop() *submission {
-	var winner *submission
-	var winnerIndex int
-	for i, v := range sr.q {
-		if v == nil {
-			continue
-		}
-		if winner == nil {
-			winner = v
-			winnerIndex = i
-			continue
-		}
-		if v.offset < winner.offset {
-			winner = v
-			winnerIndex = i
-		}
-	}
-	if winner == nil {
-		return nil
-	}
-	sr.q[winnerIndex] = nil
-	return winner
-}
-
-func (sr *serializerState) eventLoop() {
-	sr.input = make(chan *submission)
-	empty := true
-	for {
-		if empty {
-			// If the queue is empty we block on the channel to conserve CPU
-			sb := <-sr.input
-			sr.push(sb)
-			empty = false
-		}
-		select {
-		case sb := <-sr.input:
-			full := sr.push(sb)
-			if full {
-				// Queue is full, unblock the new request immediately
-				tlog.Warn.Printf("serialize_reads: queue full, forcing unblock")
-				sr.unblockOne()
-			}
-		case <-time.After(time.Microsecond * 500):
-			// Looks like we have waited out all concurrent requests.
-			empty = sr.unblockOne()
-		}
-	}
-}
-
-// Unblock a submission and wait for completion
-func (sr *serializerState) unblockOne() (empty bool) {
-	winner := sr.pop()
-	if winner == nil {
-		return true
-	}
-	sr.wg.Add(1)
-	close(winner.ch)
-	sr.wg.Wait()
-	return false
-}
-
-var serializer serializerState
-
-// InitSerializer sets up the internal serializer state and starts the event loop.
-// Called by fusefrontend.NewFS.
-func InitSerializer() {
-	serializer.input = make(chan *submission)
-	serializer.q = make([]*submission, 10)
-	go serializer.eventLoop()
-}