From 8c8b58a7de73b744392bb33bfe8ad264bcca3aa6 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Thu, 1 Nov 2018 21:14:00 +0000
Subject: [PATCH] rc: expire remote cache and fix tests under race detector

---
 fs/rc/cache.go      | 55 +++++++++++++++++++++++++++++++++++++--------
 fs/rc/cache_test.go | 33 ++++++++++++++++++++++++++-
 fs/rc/job_test.go   | 23 +++++++++++++++++++
 3 files changed, 101 insertions(+), 10 deletions(-)

diff --git a/fs/rc/cache.go b/fs/rc/cache.go
index 6d7cf48bd..af3aac230 100644
--- a/fs/rc/cache.go
+++ b/fs/rc/cache.go
@@ -4,29 +4,66 @@ package rc
 
 import (
 	"sync"
+	"time"
 
 	"github.com/ncw/rclone/fs"
 )
 
 var (
-	fsCacheMu sync.Mutex
-	fsCache   = map[string]fs.Fs{}
-	fsNewFs   = fs.NewFs // for tests
+	fsCacheMu           sync.Mutex
+	fsCache             = map[string]*cacheEntry{}
+	fsNewFs             = fs.NewFs // for tests
+	expireRunning       = false
+	cacheExpireDuration = 300 * time.Second // expire the cache entry when it is older than this
+	cacheExpireInterval = 60 * time.Second  // interval to run the cache expire
 )
 
+type cacheEntry struct {
+	f        fs.Fs
+	fsString string
+	lastUsed time.Time
+}
+
 // GetCachedFs gets a fs.Fs named fsString either from the cache or creates it afresh
 func GetCachedFs(fsString string) (f fs.Fs, err error) {
 	fsCacheMu.Lock()
 	defer fsCacheMu.Unlock()
-
-	f = fsCache[fsString]
-	if f == nil {
+	entry, ok := fsCache[fsString]
+	if !ok {
 		f, err = fsNewFs(fsString)
-		if err == nil {
-			fsCache[fsString] = f
+		if err != nil {
+			return nil, err
+		}
+		entry = &cacheEntry{
+			f:        f,
+			fsString: fsString,
+		}
+		fsCache[fsString] = entry
+	}
+	entry.lastUsed = time.Now()
+	if !expireRunning {
+		time.AfterFunc(cacheExpireInterval, cacheExpire)
+		expireRunning = true
+	}
+	return entry.f, err
+}
+
+// cacheExpire expires any entries that haven't been used recently
+func cacheExpire() {
+	fsCacheMu.Lock()
+	defer fsCacheMu.Unlock()
+	now := time.Now()
+	for fsString, entry := range fsCache {
+		if now.Sub(entry.lastUsed) > cacheExpireDuration {
+			delete(fsCache, fsString)
 		}
 	}
-	return f, err
+	if len(fsCache) != 0 {
+		time.AfterFunc(cacheExpireInterval, cacheExpire)
+		expireRunning = true
+	} else {
+		expireRunning = false
+	}
 }
 
 // GetFsNamed gets a fs.Fs named fsName either from the cache or creates it afresh
diff --git a/fs/rc/cache_test.go b/fs/rc/cache_test.go
index 07c696bca..6b9bab6be 100644
--- a/fs/rc/cache_test.go
+++ b/fs/rc/cache_test.go
@@ -2,6 +2,7 @@ package rc
 
 import (
 	"testing"
+	"time"
 
 	"github.com/ncw/rclone/fs"
 	"github.com/ncw/rclone/fstest/mockfs"
@@ -22,7 +23,10 @@ func mockNewFs(t *testing.T) func() {
 	}
 	return func() {
 		fsNewFs = oldFsNewFs
-		fsCache = map[string]fs.Fs{}
+		fsCacheMu.Lock()
+		fsCache = map[string]*cacheEntry{}
+		expireRunning = false
+		fsCacheMu.Unlock()
 	}
 }
 
@@ -42,6 +46,33 @@ func TestGetCachedFs(t *testing.T) {
 	assert.Equal(t, f, f2)
 }
 
+func TestCacheExpire(t *testing.T) {
+	defer mockNewFs(t)()
+
+	cacheExpireInterval = time.Millisecond
+	assert.Equal(t, false, expireRunning)
+
+	_, err := GetCachedFs("/")
+	require.NoError(t, err)
+
+	fsCacheMu.Lock()
+	entry := fsCache["/"]
+
+	assert.Equal(t, 1, len(fsCache))
+	fsCacheMu.Unlock()
+	cacheExpire()
+	fsCacheMu.Lock()
+	assert.Equal(t, 1, len(fsCache))
+	entry.lastUsed = time.Now().Add(-cacheExpireDuration - 60*time.Second)
+	assert.Equal(t, true, expireRunning)
+	fsCacheMu.Unlock()
+	time.Sleep(10 * time.Millisecond)
+	fsCacheMu.Lock()
+	assert.Equal(t, false, expireRunning)
+	assert.Equal(t, 0, len(fsCache))
+	fsCacheMu.Unlock()
+}
+
 func TestGetFsNamed(t *testing.T) {
 	defer mockNewFs(t)()
 
diff --git a/fs/rc/job_test.go b/fs/rc/job_test.go
index 5c9b56446..3017057f8 100644
--- a/fs/rc/job_test.go
+++ b/fs/rc/job_test.go
@@ -1,6 +1,7 @@
 package rc
 
 import (
+	"runtime"
 	"testing"
 	"time"
 
@@ -19,9 +20,13 @@ func TestJobsKickExpire(t *testing.T) {
 	jobs.expireInterval = time.Millisecond
 	assert.Equal(t, false, jobs.expireRunning)
 	jobs.kickExpire()
+	jobs.mu.Lock()
 	assert.Equal(t, true, jobs.expireRunning)
+	jobs.mu.Unlock()
 	time.Sleep(10 * time.Millisecond)
+	jobs.mu.Lock()
 	assert.Equal(t, false, jobs.expireRunning)
+	jobs.mu.Unlock()
 }
 
 func TestJobsExpire(t *testing.T) {
@@ -37,11 +42,15 @@ func TestJobsExpire(t *testing.T) {
 	assert.Equal(t, 1, len(jobs.jobs))
 	jobs.Expire()
 	assert.Equal(t, 1, len(jobs.jobs))
+	jobs.mu.Lock()
 	job.EndTime = time.Now().Add(-expireDuration - 60*time.Second)
 	assert.Equal(t, true, jobs.expireRunning)
+	jobs.mu.Unlock()
 	time.Sleep(10 * time.Millisecond)
+	jobs.mu.Lock()
 	assert.Equal(t, false, jobs.expireRunning)
 	assert.Equal(t, 0, len(jobs.jobs))
+	jobs.mu.Unlock()
 }
 
 var noopFn = func(in Params) (Params, error) {
@@ -127,13 +136,27 @@ func TestJobRunPanic(t *testing.T) {
 	jobs := newJobs()
 	job := jobs.NewJob(boom, Params{})
 	<-wait
+	runtime.Gosched() // yield to make sure job is updated
 
+	// Wait a short time for the panic to propagate
+	for i := uint(0); i < 10; i++ {
+		job.mu.Lock()
+		e := job.Error
+		job.mu.Unlock()
+		if e != "" {
+			break
+		}
+		time.Sleep(time.Millisecond << i)
+	}
+
+	job.mu.Lock()
 	assert.Equal(t, false, job.EndTime.IsZero())
 	assert.Equal(t, Params{}, job.Output)
 	assert.NotEqual(t, 0.0, job.Duration)
 	assert.Equal(t, "panic received: boom", job.Error)
 	assert.Equal(t, false, job.Success)
 	assert.Equal(t, true, job.Finished)
+	job.mu.Unlock()
 }
 
 func TestJobsNewJob(t *testing.T) {