20318: Sync cache state after 1% churn instead of 5 minute timer.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@curii.com>

diff --git a/sdk/go/arvados/keep_cache.go b/sdk/go/arvados/keep_cache.go
index 1d12f4cdc66035216eb4fccc09f5c2f7fca6f95d..b6b2a9da669f49ed292ddbdf4b412958333857c4 100644 (file)
--- a/sdk/go/arvados/keep_cache.go
+++ b/sdk/go/arvados/keep_cache.go
@@ -61,7 +61,6 @@ type sharedCache struct {
        maxSize ByteSizeOrPercent
 
        tidying        int32 // see tidy()
-       tidyHoldUntil  time.Time
        defaultMaxSize int64
 
        // The "heldopen" fields are used to open cache files for
@@ -79,8 +78,10 @@ type sharedCache struct {
        writingCond *sync.Cond
        writingLock sync.Mutex
 
-       sizeMeasured  int64 // actual size on disk after last tidy(); zero if not measured yet
-       sizeEstimated int64 // last measured size, plus files we have written since
+       sizeMeasured    int64 // actual size on disk after last tidy(); zero if not measured yet
+       sizeEstimated   int64 // last measured size, plus files we have written since
+       lastFileCount   int64 // number of files on disk at last count
+       writesSinceTidy int64 // number of files written since last tidy()
 }
 
 type writeprogress struct {
@@ -97,9 +98,8 @@ type openFileEnt struct {
 }
 
 const (
-       cacheFileSuffix  = ".keepcacheblock"
-       tmpFileSuffix    = ".tmp"
-       tidyHoldDuration = 5 * time.Minute // time to re-check cache size even if estimated size is below max
+       cacheFileSuffix = ".keepcacheblock"
+       tmpFileSuffix   = ".tmp"
 )
 
 func (cache *DiskCache) setup() {
@@ -557,6 +557,7 @@ func (cache *DiskCache) BlockRead(ctx context.Context, opts BlockReadOptions) (i
 // Start a tidy() goroutine, unless one is already running / recently
 // finished.
 func (cache *DiskCache) gotidy() {
+       writes := atomic.AddInt64(&cache.writesSinceTidy, 1)
        // Skip if another tidy goroutine is running in this process.
        n := atomic.AddInt32(&cache.tidying, 1)
        if n != 1 {
@@ -564,17 +565,18 @@ func (cache *DiskCache) gotidy() {
                return
        }
        // Skip if sizeEstimated is based on an actual measurement and
-       // is below maxSize, and we haven't reached the "recheck
-       // anyway" time threshold.
+       // is below maxSize, and we haven't done very many writes
+       // since last tidy (defined as 1% of number of cache files at
+       // last count).
        if cache.sizeMeasured > 0 &&
                atomic.LoadInt64(&cache.sizeEstimated) < atomic.LoadInt64(&cache.defaultMaxSize) &&
-               time.Now().Before(cache.tidyHoldUntil) {
+               writes < cache.lastFileCount/100 {
                atomic.AddInt32(&cache.tidying, -1)
                return
        }
        go func() {
                cache.tidy()
-               cache.tidyHoldUntil = time.Now().Add(tidyHoldDuration)
+               atomic.StoreInt64(&cache.writesSinceTidy, 0)
                atomic.AddInt32(&cache.tidying, -1)
        }()
 }
@@ -677,6 +679,7 @@ func (cache *DiskCache) tidy() {
        if totalsize <= maxsize || len(ents) == 1 {
                atomic.StoreInt64(&cache.sizeMeasured, totalsize)
                atomic.StoreInt64(&cache.sizeEstimated, totalsize)
+               cache.lastFileCount = int64(len(ents))
                return
        }
 
@@ -710,4 +713,5 @@ func (cache *DiskCache) tidy() {
        }
        atomic.StoreInt64(&cache.sizeMeasured, totalsize)
        atomic.StoreInt64(&cache.sizeEstimated, totalsize)
+       cache.lastFileCount = int64(len(ents) - deleted)
 }