eden debug blob add option to show blob contents from all locations

Summary:
EdenFS now supports fetching blobs from multiple locations. It certainly would
have been helpful to be able to see blob contents from all locations all at
once while debugging reports of corrupted file content recently.

Lets add an option to `eden debug blob` so that we cans see data from multiple
places at once.

Reviewed By: chadaustin

Differential Revision: D41165544

fbshipit-source-id: 421fc8841a531894715ff5cbb3786e1003782666

eden/fs/cli/debug.py

@@ -48,6 +48,7 @@ from facebook.eden.ttypes import (
     MountId,
     NoValueForKeyError,
     ScmBlobOrError,
+    ScmBlobWithOrigin,
     SyncBehavior,
     TimeSpec,
     TreeInodeDebugInfo,
@@ -367,12 +368,74 @@ class BlobCmd(Subcmd):
             default=False,
             help="Only fetch the data from the servers. ",
         )
+        group.add_argument(
+            "-a",
+            "--all",
+            action="store_true",
+            default=False,
+            help="Fetch the blob from all storage locations and display their contents. ",
+        )
         parser.add_argument(
             "mount",
             help="The EdenFS mount point path.",
         )
         parser.add_argument("id", help="The blob ID")
 
+    def origin_to_text(self, origin: DataFetchOrigin) -> str:
+        if origin == DataFetchOrigin.MEMORY_CACHE:
+            return "object cache"
+        elif origin == DataFetchOrigin.DISK_CACHE:
+            return "local store"
+        elif origin == DataFetchOrigin.LOCAL_BACKING_STORE:
+            return "hgcache"
+        elif origin == DataFetchOrigin.REMOTE_BACKING_STORE:
+            return "servers"
+        elif origin == DataFetchOrigin.ANYWHERE:
+            return "EdenFS production data fetching process"
+        return "<unknown>"
+
+    def print_blob_or_error(self, blobOrError: ScmBlobOrError) -> None:
+        if blobOrError.getType() == ScmBlobOrError.BLOB:
+            sys.stdout.buffer.write(blobOrError.get_blob())
+        else:
+            error = blobOrError.get_error()
+            sys.stdout.buffer.write(f"ERROR fetching data: {error}\n".encode())
+
+    def print_all_blobs(self, blobs: List[ScmBlobWithOrigin]) -> None:
+        non_error_blobs = []
+        for blob in blobs:
+            blob_found = blob.blob.getType() == ScmBlobOrError.BLOB
+            pretty_origin = self.origin_to_text(blob.origin)
+            pretty_blob_found = "hit" if blob_found else "miss"
+            print(f"{pretty_origin}: {pretty_blob_found}")
+            if blob_found:
+                non_error_blobs.append(blob)
+
+        if len(non_error_blobs) == 0:
+            return
+        if len(non_error_blobs) == 1:
+            print("\n")
+            sys.stdout.buffer.write(non_error_blobs[0].blob.get_blob())
+            return
+
+        blobs_match = True
+        for blob in non_error_blobs[1::]:
+            if blob.blob.get_blob() != non_error_blobs[0].blob.get_blob():
+                blobs_match = False
+                break
+
+        if blobs_match:
+            print("\nAll blobs match :) \n")
+            sys.stdout.buffer.write(non_error_blobs[0].blob.get_blob())
+        else:
+            print("\n!!!!! Blob mismatch !!!!! \n")
+            for blob in non_error_blobs:
+                prety_fromwhere = self.origin_to_text(blob.origin)
+                print(f"Blob from {prety_fromwhere}\n")
+                print("-----------------------------\n")
+                sys.stdout.buffer.write(blob.blob.get_blob())
+                print("\n-----------------------------\n\n")
+
     def run(self, args: argparse.Namespace) -> int:
         instance, checkout, _rel_path = cmd_util.require_checkout(args, args.mount)
         blob_id = parse_object_id(args.id)
@@ -386,6 +449,14 @@ class BlobCmd(Subcmd):
             origin_flags = DataFetchOrigin.LOCAL_BACKING_STORE
         elif args.remote_only:
             origin_flags = DataFetchOrigin.REMOTE_BACKING_STORE
+        elif args.all:
+            origin_flags = (
+                DataFetchOrigin.MEMORY_CACHE
+                | DataFetchOrigin.DISK_CACHE
+                | DataFetchOrigin.LOCAL_BACKING_STORE
+                | DataFetchOrigin.REMOTE_BACKING_STORE
+                | DataFetchOrigin.ANYWHERE
+            )
 
         with instance.get_thrift_client_legacy() as client:
             data = client.debugGetBlob(
@@ -395,11 +466,11 @@ class BlobCmd(Subcmd):
                     origin_flags,
                 )
             )
-        blobOrError = data.blobs[0].blob
+            if args.all:
-        if blobOrError.getType() == ScmBlobOrError.BLOB:
+                self.print_all_blobs(data.blobs)
-            sys.stdout.buffer.write(blobOrError.get_blob())
+            else:
-        else:
+                self.print_blob_or_error(data.blobs[0].blob)
-            raise blobOrError.get_error()
+
         return 0