X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/02adf6134d262d17066dbc48d3fb85c8861c8349..8a27fe370239ecb8e50d53f46b45ed61203a35ca:/sdk/go/keepclient/block_cache.go

diff --git a/sdk/go/keepclient/block_cache.go b/sdk/go/keepclient/block_cache.go
index 1849fa2ce3..bac4a24fd5 100644
--- a/sdk/go/keepclient/block_cache.go
+++ b/sdk/go/keepclient/block_cache.go
@@ -7,6 +7,8 @@ package keepclient
 import (
 	"io"
 	"sort"
+	"strconv"
+	"strings"
 	"sync"
 	"time"
 )
@@ -18,9 +20,8 @@ type BlockCache struct {
 	// default size (currently 4) is used instead.
 	MaxBlocks int
 
-	cache     map[string]*cacheBlock
-	mtx       sync.Mutex
-	setupOnce sync.Once
+	cache map[string]*cacheBlock
+	mtx   sync.Mutex
 }
 
 const defaultMaxBlocks = 4
@@ -50,12 +51,34 @@ func (c *BlockCache) Sweep() {
 	}
 }
 
+// ReadAt returns data from the cache, first retrieving it from Keep if
+// necessary.
+func (c *BlockCache) ReadAt(kc *KeepClient, locator string, p []byte, off int) (int, error) {
+	buf, err := c.Get(kc, locator)
+	if err != nil {
+		return 0, err
+	}
+	if off > len(buf) {
+		return 0, io.ErrUnexpectedEOF
+	}
+	return copy(p, buf[off:]), nil
+}
+
 // Get returns data from the cache, first retrieving it from Keep if
 // necessary.
 func (c *BlockCache) Get(kc *KeepClient, locator string) ([]byte, error) {
-	c.setupOnce.Do(c.setup)
 	cacheKey := locator[:32]
+	bufsize := BLOCKSIZE
+	if parts := strings.SplitN(locator, "+", 3); len(parts) >= 2 {
+		datasize, err := strconv.ParseInt(parts[1], 10, 32)
+		if err == nil && datasize >= 0 {
+			bufsize = int(datasize)
+		}
+	}
 	c.mtx.Lock()
+	if c.cache == nil {
+		c.cache = make(map[string]*cacheBlock)
+	}
 	b, ok := c.cache[cacheKey]
 	if !ok || b.err != nil {
 		b = &cacheBlock{
@@ -67,7 +90,7 @@ func (c *BlockCache) Get(kc *KeepClient, locator string) ([]byte, error) {
 			rdr, size, _, err := kc.Get(locator)
 			var data []byte
 			if err == nil {
-				data := make([]byte, size, BLOCKSIZE)
+				data = make([]byte, size, bufsize)
 				_, err = io.ReadFull(rdr, data)
 				err2 := rdr.Close()
 				if err == nil {
@@ -93,13 +116,9 @@ func (c *BlockCache) Get(kc *KeepClient, locator string) ([]byte, error) {
 	return b.data, b.err
 }
 
-func (c *BlockCache) setup() {
-	c.cache = make(map[string]*cacheBlock)
-}
-
 func (c *BlockCache) Clear() {
 	c.mtx.Lock()
-	c.setup()
+	c.cache = nil
 	c.mtx.Unlock()
 }