vfs: reduce memory use by embedding sync.Cond

vfs/read.go

@@ -20,7 +20,7 @@ type ReadFileHandle struct {
 	baseHandle
 	done        func(ctx context.Context, err error)
 	mu          sync.Mutex
-	cond        *sync.Cond // cond lock for out of sequence reads
+	cond        sync.Cond // cond lock for out of sequence reads
 	closed      bool       // set if handle has been closed
 	r           *accounting.Account
 	readCalled  bool  // set if read has been called
@@ -63,7 +63,7 @@ func newReadFileHandle(f *File) (*ReadFileHandle, error) {
 		size:        nonNegative(o.Size()),
 		sizeUnknown: o.Size() < 0,
 	}
-	fh.cond = sync.NewCond(&fh.mu)
+	fh.cond = sync.Cond{L: &fh.mu}
 	return fh, nil
 }
 
@@ -267,7 +267,7 @@ func (fh *ReadFileHandle) readAt(p []byte, off int64) (n int, err error) {
 		maxBuf = len(p)
 	}
 	if gap := off - fh.offset; gap > 0 && gap < int64(8*maxBuf) {
-		waitSequential("read", fh.remote, fh.cond, fh.file.VFS().Opt.ReadWait, &fh.offset, off)
+		waitSequential("read", fh.remote, &fh.cond, fh.file.VFS().Opt.ReadWait, &fh.offset, off)
 	}
 	doSeek := off != fh.offset
 	if doSeek && fh.noSeek {

vfs/vfscache/cache.go

@@ -52,7 +52,7 @@ type Cache struct {
 	avFn       AddVirtualFn         // if set, can be called to add dir entries
 
 	mu            sync.Mutex       // protects the following variables
-	cond          *sync.Cond       // cond lock for synchronous cache cleaning
+	cond          sync.Cond        // cond lock for synchronous cache cleaning
 	item          map[string]*Item // files/directories in the cache
 	errItems      map[string]error // items in error state
 	used          int64            // total size of files in the cache
@@ -139,7 +139,7 @@ func New(ctx context.Context, fremote fs.Fs, opt *vfscommon.Options, avFn AddVir
 
 	// Create a channel for cleaner to be kicked upon out of space con
 	c.kick = make(chan struct{}, 1)
-	c.cond = sync.NewCond(&c.mu)
+	c.cond = sync.Cond{L: &c.mu}
 
 	go c.cleaner(ctx)
 

vfs/vfscache/item.go

@@ -57,7 +57,7 @@ type Item struct {
 	// read only
 	c               *Cache                   // cache this is part of
 	mu              sync.Mutex               // protect the variables
-	cond            *sync.Cond               // synchronize with cache cleaner
+	cond            sync.Cond                // synchronize with cache cleaner
 	name            string                   // name in the VFS
 	opens           int                      // number of times file is open
 	downloaders     *downloaders.Downloaders // a record of the downloaders in action - may be nil
@@ -138,7 +138,7 @@ func newItem(c *Cache, name string) (item *Item) {
 			ATime:   now,
 		},
 	}
-	item.cond = sync.NewCond(&item.mu)
+	item.cond = sync.Cond{L: &item.mu}
 	// check the cache file exists
 	osPath := c.toOSPath(name)
 	fi, statErr := os.Stat(osPath)

vfs/write.go

@@ -15,7 +15,7 @@ import (
 type WriteFileHandle struct {
 	baseHandle
 	mu          sync.Mutex
-	cond        *sync.Cond // cond lock for out of sequence writes
+	cond        sync.Cond // cond lock for out of sequence writes
 	closed      bool       // set if handle has been closed
 	remote      string
 	pipeWriter  *io.PipeWriter
@@ -43,7 +43,7 @@ func newWriteFileHandle(d *Dir, f *File, remote string, flags int) (*WriteFileHa
 		result: make(chan error, 1),
 		file:   f,
 	}
-	fh.cond = sync.NewCond(&fh.mu)
+	fh.cond = sync.Cond{L: &fh.mu}
 	fh.file.addWriter(fh)
 	return fh, nil
 }
@@ -130,7 +130,7 @@ func (fh *WriteFileHandle) writeAt(p []byte, off int64) (n int, err error) {
 		return 0, ECLOSED
 	}
 	if fh.offset != off {
-		waitSequential("write", fh.remote, fh.cond, fh.file.VFS().Opt.WriteWait, &fh.offset, off)
+		waitSequential("write", fh.remote, &fh.cond, fh.file.VFS().Opt.WriteWait, &fh.offset, off)
 	}
 	if fh.offset != off {
 		fs.Errorf(fh.remote, "WriteFileHandle.Write: can't seek in file without --vfs-cache-mode >= writes")