stats: add new counters to existing docs

Summary:
# Context

I added new stats in D58492412, so now I have to document them. I've updated the wiki, but I still need to update the markdown docs stored in the repo.

# This diff

Updates the stats docs to match reality.

Reviewed By: fanzeyi

Differential Revision: D59932131

fbshipit-source-id: fe17c2ee986e182d00d35121827346e5c210ba1a

Author: MichaelCuevas

eden/fs/docs/stats/ObjectStoreStats.md

@@ -2,33 +2,37 @@
 
 1. `Duration get{xxx}{"store.get_{xxx}_us"}` :
 
-The whole duration of get{xxx} xxx (blob, blobmetadata, tree) in ObjectStore.
-Consider that ObjectStore can get Object from memory (MemoryCache), LocalStore
-(OndiskCache), or BackingStore
+The whole duration of get{xxx} xxx (blob, blobmetadata, tree, treemetadata) in
+ObjectStore. Consider that ObjectStore can get Object from memory (MemoryCache),
+LocalStore (OndiskCache), or BackingStore
 
 2. `Counter get{xxx}FromMemory{"object_store.get_{xxx}.memory"}` :
 
-Count the number of xxx (blob, blobmetadata, tree) that are successfully
-obtained from MemoryCache. It doesn’t check the local store either.
+Count the number of xxx (blob, blobmetadata, tree, treemetadata) that are
+successfully obtained from MemoryCache. It doesn’t check the local store either.
 
 3. `Counter get{xxx}FromLocalStore{"object_store.get_{xxx}.local_store"}` :
 
 Count the number of xxx (blob, blobmetadata, tree) that are successfully
-obtained from LocalStore (OnDiskCache). It doesn’t hit the BackingStore.
+obtained from LocalStore (OnDiskCache). It doesn’t hit the BackingStore. Note:
+TreeMetadata is not stored in the local store, so the tree_metadata counter
+doesn't exist.
 
 4. `Counter get{xxx}FromBackingStore{"object_store.get_{xxx}.backing_store"}` :
 
-Count the number of xxx (blob, blobmetadata, tree) that are obtained from
-BackingStore.
+Count the number of xxx (blob, blobmetadata, tree, treemetadata) that are
+obtained from BackingStore.
 
 5. `Counter get{xxx}Failed{"object_store.get_{xxx}_failed"}` :
 
-Count the number of xxx (blob, blobmetadata, tree) cannot be fetched.
+Count the number of xxx (blob, blobmetadata, tree, treemetadata) cannot be
+fetched.
 
 6. `Counter getBlobMetadataFromBlob{"object_store.get_blob_metadata.blob"}` :
 
 Count the number of BlobMetadata that cannot be obtained from BackingStore, but
-we obtained Blob and from Blob we found the BlobMetadata.
+we obtained Blob and from Blob we found the BlobMetadata. Note: TreeMetadata
+cannot be computed locally, so the tree version of this counter does not exist.
 
 7. `Duration getRootTree{"store.get_root_tree_us"}` :
 

eden/fs/docs/stats/SaplingBackingStoreStats.md

@@ -2,15 +2,15 @@
 
 1. `Duration get{xxx}{"store.sapling.get_{xxx}_us"}` :
 
-Duration of the whole get xxx (blob, blobmetadata, tree)
+Duration of the whole get xxx (blob, blobmetadata, tree, treemetadata)
 SaplingBackingStore::get{xxx} in Microsecond. This includes looking in local
 first then if not found prepare the request, enqueue the request and then mark
 it as finished when it is fulfilled.
 
 2. `Duration fetch{xxx}{"store.sapling.fetch_{xxx}_us"}` :
 
-Duration of fetching xxx (blob, blobmetadata, tree) requests from the network in
-Microsecond.
+Duration of fetching xxx (blob, blobmetadata, tree, treemetadata) requests from
+the network in Microsecond.
 
 3. `Duration getRootTree{"store.sapling.get_root_tree_us"}` :
 
@@ -23,21 +23,23 @@ Duration of getting a manifest for Root from the Backing Store in Microsecond.
 
 5. `Counter fetch{xxx}Local{"store.sapling.fetch_{xxx}_local"}` :
 
-Number of xxx (blob, blobmetadata, tree) fetching locally from hgcache
+Number of xxx (blob, blobmetadata, tree, treemetadata) fetching locally from
+hgcache
 
 6. `Counter fetch{xxx}Remote{"store.sapling.fetch_{xxx}_remote"}` :
 
-Number of xxx (blob, blobmetadata, tree) fetching remotely from the network
-(EdenAPI)
+Number of xxx (blob, blobmetadata, tree, treemetadata) fetching remotely from
+the network (EdenAPI)
 
 7. `Counter fetch{xxx}Success{"store.sapling.fetch_{xxx}_success"}` :
 
-Number of xxx (blob, blobmetadata, tree) that fetch successfully in the first
-try. (It could be local or remote)
+Number of xxx (blob, blobmetadata, tree, treemetadata) that fetch successfully
+in the first try. (It could be local or remote)
 
 8. `Counter fetch{xxx}Failure{"store.sapling.fetch_{xxx}_failure"}` :
 
-Number of xxx (blob, blobmetadata, tree) that failed in the first fetch try.
+Number of xxx (blob, blobmetadata, tree, treemetadata) that failed in the first
+fetch try.
 
 9. `Counter fetch{xxx}RetrySuccess{"store.sapling.fetch_{xxx}_retry_success"}` :