Ensure disk cache root exists

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.

Closes #19202.

PiperOrigin-RevId: 555429326
Change-Id: Ifcfa8c686df30c03c9fca24be860b2db780a6374

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

@@ -142,9 +142,6 @@ private static DiskCacheClient createDiskCache(
       throws IOException {
     Path cacheDir =
         workingDirectory.getRelative(Preconditions.checkNotNull(diskCachePath, "diskCachePath"));
-    if (!cacheDir.exists()) {
-      cacheDir.createDirectoryAndParents();
-    }
     return new DiskCacheClient(cacheDir, verifyDownloads, digestUtil);
   }
 
@@ -157,12 +154,6 @@ private static RemoteCacheClient createDiskAndHttpCache(
       DigestUtil digestUtil,
       RemoteRetrier retrier)
       throws IOException {
-    Path cacheDir =
-        workingDirectory.getRelative(Preconditions.checkNotNull(diskCachePath, "diskCachePath"));
-    if (!cacheDir.exists()) {
-      cacheDir.createDirectoryAndParents();
-    }
-
     RemoteCacheClient httpCache = createHttp(options, cred, authAndTlsOptions, digestUtil, retrier);
     return createDiskAndRemoteClient(
         workingDirectory, diskCachePath, options.remoteVerifyDownloads, digestUtil, httpCache);

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

@@ -55,7 +55,8 @@ public class DiskCacheClient implements RemoteCacheClient {
    * @param verifyDownloads whether verify the digest of downloaded content are the same as the
    *     digest used to index that file.
    */
-  public DiskCacheClient(Path root, boolean verifyDownloads, DigestUtil digestUtil) {
+  public DiskCacheClient(Path root, boolean verifyDownloads, DigestUtil digestUtil)
+      throws IOException {
     this.verifyDownloads = verifyDownloads;
     this.digestUtil = digestUtil;
 
@@ -66,6 +67,8 @@ public DiskCacheClient(Path root, boolean verifyDownloads, DigestUtil digestUtil
           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(cacheDir, /* verifyDownloads= */ true, digestUtil),