From b83ca9c921019fc3b790dabb6198bb77ef2f9a34 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Mon, 30 Aug 2021 09:39:57 +0200
Subject: 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
---
 internal/serialize_reads/sr.go | 150 -----------------------------------------
 1 file changed, 150 deletions(-)
 delete mode 100644 internal/serialize_reads/sr.go

(limited to 'internal/serialize_reads')

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()
-}
-- 
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