erasure pools enable faster checks for file not found (#11799)

For operations that require the object to exist make it possible to 
detect if the file isn't found in *any* pool.

This will allow these to return the error early without having to re-check.

cmd/erasure-server-pool.go

@@ -244,6 +244,50 @@ func (z *erasureServerPools) getServerPoolsAvailableSpace(ctx context.Context, s
 	return serverPools
 }
 
+// getPoolIdxExisting returns the (first) found object pool index containing an object.
+// If the object exists, but the latest version is a delete marker, the index with it is still returned.
+// If the object does not exist ObjectNotFound error is returned.
+// If any other error is found, it is returned.
+// The check is skipped if there is only one zone, and 0, nil is always returned in that case.
+func (z *erasureServerPools) getPoolIdxExisting(ctx context.Context, bucket, object string) (idx int, err error) {
+	if z.SinglePool() {
+		return 0, nil
+	}
+
+	errs := make([]error, len(z.serverPools))
+	objInfos := make([]ObjectInfo, len(z.serverPools))
+
+	var wg sync.WaitGroup
+	for i, pool := range z.serverPools {
+		wg.Add(1)
+		go func(i int, pool *erasureSets) {
+			defer wg.Done()
+			objInfos[i], errs[i] = pool.GetObjectInfo(ctx, bucket, object, ObjectOptions{})
+		}(i, pool)
+	}
+	wg.Wait()
+
+	for i, err := range errs {
+		if err == nil {
+			return i, nil
+		}
+		if isErrObjectNotFound(err) {
+			// No object exists or its a delete marker,
+			// check objInfo to confirm.
+			if objInfos[i].DeleteMarker && objInfos[i].Name != "" {
+				return i, nil
+			}
+
+			// objInfo is not valid, truly the object doesn't
+			// exist proceed to next pool.
+			continue
+		}
+		return -1, err
+	}
+
+	return -1, toObjectErr(errFileNotFound, bucket, object)
+}
+
 // getPoolIdx returns the found previous object and its corresponding pool idx,
 // if none are found falls back to most available space pool.
 func (z *erasureServerPools) getPoolIdx(ctx context.Context, bucket, object string, size int64) (idx int, err error) {
@@ -715,8 +759,7 @@ func (z *erasureServerPools) DeleteObject(ctx context.Context, bucket string, ob
 		return z.serverPools[0].DeleteObject(ctx, bucket, object, opts)
 	}
 
-	// We don't know the size here set 1GiB atleast.
+	idx, err := z.getPoolIdxExisting(ctx, bucket, object)
-	idx, err := z.getPoolIdx(ctx, bucket, object, 1<<30)
 	if err != nil {
 		return objInfo, err
 	}
@@ -739,7 +782,11 @@ func (z *erasureServerPools) DeleteObjects(ctx context.Context, bucket string, o
 	origIndexMap := map[int][]int{}
 	if !z.SinglePool() {
 		for j, obj := range objects {
-			idx, err := z.getPoolIdx(ctx, bucket, obj.ObjectName, 1<<30)
+			idx, err := z.getPoolIdxExisting(ctx, bucket, obj.ObjectName)
+			if isErrObjectNotFound(err) {
+				derrs[j] = err
+				continue
+			}
 			if err != nil {
 				// Unhandled errors return right here.
 				for i := range derrs {
@@ -1734,7 +1781,7 @@ func (z *erasureServerPools) PutObjectTags(ctx context.Context, bucket, object s
 	}
 
 	// We don't know the size here set 1GiB atleast.
-	idx, err := z.getPoolIdx(ctx, bucket, object, 1<<30)
+	idx, err := z.getPoolIdxExisting(ctx, bucket, object)
 	if err != nil {
 		return ObjectInfo{}, err
 	}
@@ -1749,8 +1796,7 @@ func (z *erasureServerPools) DeleteObjectTags(ctx context.Context, bucket, objec
 		return z.serverPools[0].DeleteObjectTags(ctx, bucket, object, opts)
 	}
 
-	// We don't know the size here set 1GiB atleast.
+	idx, err := z.getPoolIdxExisting(ctx, bucket, object)
-	idx, err := z.getPoolIdx(ctx, bucket, object, 1<<30)
 	if err != nil {
 		return ObjectInfo{}, err
 	}
@@ -1765,8 +1811,7 @@ func (z *erasureServerPools) GetObjectTags(ctx context.Context, bucket, object s
 		return z.serverPools[0].GetObjectTags(ctx, bucket, object, opts)
 	}
 
-	// We don't know the size here set 1GiB atleast.
+	idx, err := z.getPoolIdxExisting(ctx, bucket, object)
-	idx, err := z.getPoolIdx(ctx, bucket, object, 1<<30)
 	if err != nil {
 		return nil, err
 	}