18051: Add debug logging for webdav cache.

[arvados.git] / services / keepstore / handlers.go

diff --git a/services/keepstore/handlers.go b/services/keepstore/handlers.go
index 81f7fcd123704f53f6399f75023bf82768ba387e..910033ebb1d8408c90a4bde441d7edc8d99b109a 100644 (file)
--- a/services/keepstore/handlers.go
+++ b/services/keepstore/handlers.go
@@ -837,7 +837,7 @@ func (pr *putProgress) Copy() *putProgress {
        return &cp
 }
 
-func newPutResult(classes []string) putProgress {
+func newPutProgress(classes []string) putProgress {
        pr := putProgress{
                classNeeded: make(map[string]bool, len(classes)),
                classTodo:   make(map[string]bool, len(classes)),
@@ -853,33 +853,29 @@ func newPutResult(classes []string) putProgress {
        return pr
 }
 
-// PutBlock Stores the BLOCK (identified by the content id HASH) in Keep.
+// PutBlock stores the given block on one or more volumes.
 //
-// PutBlock(ctx, block, hash)
-//   Stores the BLOCK (identified by the content id HASH) in Keep.
+// The MD5 checksum of the block must match the given hash.
 //
-//   The MD5 checksum of the block must be identical to the content id HASH.
-//   If not, an error is returned.
+// The block is written to each writable volume (ordered by priority
+// and then UUID, see volume.go) until at least one replica has been
+// stored in each of the requested storage classes.
 //
-//   PutBlock stores the BLOCK on the first Keep volume with free space.
-//   A failure code is returned to the user only if all volumes fail.
-//
-//   On success, PutBlock returns nil.
-//   On failure, it returns a KeepError with one of the following codes:
-//
-//   500 Collision
-//          A different block with the same hash already exists on this
-//          Keep server.
-//   422 MD5Fail
-//          The MD5 hash of the BLOCK does not match the argument HASH.
-//   503 Full
-//          There was not enough space left in any Keep volume to store
-//          the object.
-//   500 Fail
-//          The object could not be stored for some other reason (e.g.
-//          all writes failed). The text of the error message should
-//          provide as much detail as possible.
+// The returned error, if any, is a KeepError with one of the
+// following codes:
 //
+// 500 Collision
+//        A different block with the same hash already exists on this
+//        Keep server.
+// 422 MD5Fail
+//        The MD5 hash of the BLOCK does not match the argument HASH.
+// 503 Full
+//        There was not enough space left in any Keep volume to store
+//        the object.
+// 500 Fail
+//        The object could not be stored for some other reason (e.g.
+//        all writes failed). The text of the error message should
+//        provide as much detail as possible.
 func PutBlock(ctx context.Context, volmgr *RRVolumeManager, block []byte, hash string, wantStorageClasses []string) (putProgress, error) {
        log := ctxlog.FromContext(ctx)
 
@@ -890,7 +886,7 @@ func PutBlock(ctx context.Context, volmgr *RRVolumeManager, block []byte, hash s
                return putProgress{}, RequestHashError
        }
 
-       result := newPutResult(wantStorageClasses)
+       result := newPutProgress(wantStorageClasses)
 
        // If we already have this data, it's intact on disk, and we
        // can update its timestamp, return success. If we have
@@ -916,7 +912,11 @@ func PutBlock(ctx context.Context, volmgr *RRVolumeManager, block []byte, hash s
        pending := result.Copy()
        var allFull atomic.Value
        allFull.Store(true)
+
+       // We hold the lock for the duration of the "each volume" loop
+       // below, except when it is released during cond.Wait().
        mtx.Lock()
+
        for _, mnt := range writables {
                // Wait until our decision to use this mount does not
                // depend on the outcome of pending writes.