Fix 2.4.2 upgrade notes formatting refs #19330

[arvados.git] / sdk / go / keepclient / block_cache.go

diff --git a/sdk/go/keepclient/block_cache.go b/sdk/go/keepclient/block_cache.go
index e841a00fa1e1f3493bff67890b2aee70181a3bca..bac4a24fd5a037d9cdcafb663612677304184c97 100644 (file)
--- 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"
 )
@@ -49,10 +51,30 @@ 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) {
        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)
@@ -68,7 +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 {