[6.4.0] Ensure disk cache root exists (#19225)

The disk cache root directory was previously being manually created in
two places before creating the disk cache client. This CL instead
ensures that the disk cache root directory is created when
createDiskCache() is called, and simplifies the other callsites.

This fixes an issue where the disk cache directory might not exist if
using --digest_function=BLAKE3.

PiperOrigin-RevId: 555429326
Change-Id: Ifcfa8c686df30c03c9fca24be860b2db780a6374

(cherry picked from commit 00dfa2e)

Co-authored-by: Tyler Williams <williams.tyler@gmail.com>

src/main/java/com/google/devtools/build/lib/remote/RemoteCacheClientFactory.java

@@ -139,9 +139,6 @@ private static DiskCacheClient createDiskCache(
       throws IOException {
     Path cacheDir =
         workingDirectory.getRelative(Preconditions.checkNotNull(diskCachePath, "diskCachePath"));
-    if (!cacheDir.exists()) {
-      cacheDir.createDirectoryAndParents();
-    }
     return new DiskCacheClient(cacheDir, verifyDownloads, checkActionResult, digestUtil);
   }
 
@@ -153,12 +150,6 @@ private static RemoteCacheClient createDiskAndHttpCache(
       AuthAndTLSOptions authAndTlsOptions,
       DigestUtil digestUtil)
       throws IOException {
-    Path cacheDir =
-        workingDirectory.getRelative(Preconditions.checkNotNull(diskCachePath, "diskCachePath"));
-    if (!cacheDir.exists()) {
-      cacheDir.createDirectoryAndParents();
-    }
-
     RemoteCacheClient httpCache = createHttp(options, cred, authAndTlsOptions, digestUtil);
     return createDiskAndRemoteClient(
         workingDirectory,

src/main/java/com/google/devtools/build/lib/remote/disk/DiskCacheClient.java

@@ -59,7 +59,7 @@ public class DiskCacheClient implements RemoteCacheClient {
    *     is {@code true} and blobs referenced by the AC are missing, ignore the AC.
    */
   public DiskCacheClient(
-      Path root, boolean verifyDownloads, boolean checkActionResult, DigestUtil digestUtil) {
+      Path root, boolean verifyDownloads, boolean checkActionResult, DigestUtil digestUtil) throws IOException {
     this.verifyDownloads = verifyDownloads;
     this.checkActionResult = checkActionResult;
     this.digestUtil = digestUtil;
@@ -71,6 +71,8 @@ public DiskCacheClient(
           root.getChild(
               Ascii.toLowerCase(digestUtil.getDigestFunction().getValueDescriptor().getName()));
     }
+
+    this.root.createDirectoryAndParents();
   }
 
   /** Returns {@code true} if the provided {@code key} is stored in the CAS. */

src/tools/remote/src/main/java/com/google/devtools/build/remote/worker/OnDiskBlobStoreCache.java

@@ -43,7 +43,8 @@ class OnDiskBlobStoreCache extends RemoteCache {
           .setSymlinkAbsolutePathStrategy(SymlinkAbsolutePathStrategy.Value.ALLOWED)
           .build();
 
-  public OnDiskBlobStoreCache(RemoteOptions options, Path cacheDir, DigestUtil digestUtil) {
+  public OnDiskBlobStoreCache(RemoteOptions options, Path cacheDir, DigestUtil digestUtil)
+      throws IOException {
     super(
         CAPABILITIES,
         new DiskCacheClient(