count fetch statistics during diff and checkout

Summary:
During checkout and stats, count every object fetch and which level of
cache it was served from.

Reviewed By: simpkins

Differential Revision: D19186333

fbshipit-source-id: fc0a74db297b9c723682e245996a7befd762f933

eden/fs/inodes/CheckoutContext.h

@@ -13,7 +13,7 @@
 #include "eden/fs/inodes/EdenMount.h"
 #include "eden/fs/inodes/InodePtrFwd.h"
 #include "eden/fs/service/gen-cpp2/eden_types.h"
-#include "eden/fs/store/IObjectStore.h"
+#include "eden/fs/store/StatsFetchContext.h"
 #include "eden/fs/utils/PathFuncs.h"
 
 namespace folly {
@@ -102,7 +102,7 @@ class CheckoutContext {
   /**
    * Return the fetch context associated with this checkout context.
    */
-  ObjectFetchContext& getFetchContext() {
+  StatsFetchContext& getFetchContext() {
     return fetchContext_;
   }
 
@@ -111,7 +111,7 @@ class CheckoutContext {
   EdenMount* const mount_;
   folly::Synchronized<EdenMount::ParentInfo>::LockedPtr parentsLock_;
   RenameLock renameLock_;
-  ObjectFetchContext fetchContext_;
+  StatsFetchContext fetchContext_;
 
   // The checkout processing may occur across many threads,
   // if some data load operations complete asynchronously on other threads.

eden/fs/inodes/EdenMount.cpp

@@ -113,7 +113,7 @@ class EdenMount::JournalDiffCallback : public DiffCallback {
                   << folly::exceptionStr(ew);
   }
 
-  FOLLY_NODISCARD Future<folly::Unit> performDiff(
+  FOLLY_NODISCARD Future<StatsFetchContext> performDiff(
       EdenMount* mount,
       TreeInodePtr rootInode,
       std::shared_ptr<const Tree> rootTree) {
@@ -127,7 +127,8 @@ class EdenMount::JournalDiffCallback : public DiffCallback {
             std::move(rootTree),
             rawContext->getToplevelIgnore(),
             false)
-        .ensure([diffContext = std::move(diffContext), rootInode]() {});
+        .thenValue([diffContext = std::move(diffContext), rootInode](
+                       folly::Unit) { return diffContext->getFetchContext(); });
   }
 
   /** moves the Unclean Path information out of this diff callback instance,
@@ -798,10 +799,9 @@ folly::Future<CheckoutResult> EdenMount::checkout(
 
         auto& fromTree = std::get<0>(treeResults);
         return journalDiffCallback->performDiff(this, getRootInode(), fromTree)
-            .thenValue([ctx, journalDiffCallback, treeResults](Unit) {
-              // TODO: Merge results from JournalDiffCallback into ctx
-              (void)ctx;
-              (void)journalDiffCallback;
+            .thenValue([ctx, journalDiffCallback, treeResults](
+                           const StatsFetchContext& diffFetchContext) {
+              ctx->getFetchContext().merge(diffFetchContext);
               return treeResults;
             });
       })

eden/fs/store/DiffContext.h

@@ -10,7 +10,7 @@
 #include <folly/Range.h>
 #include <folly/futures/Future.h>
 
-#include "eden/fs/store/IObjectStore.h"
+#include "eden/fs/store/StatsFetchContext.h"
 #include "eden/fs/utils/PathFuncs.h"
 
 namespace folly {
@@ -77,7 +77,7 @@ class DiffContext {
   const GitIgnoreStack* getToplevelIgnore() const;
   bool isCancelled() const;
   LoadFileFunction getLoadFileContentsFromPath() const;
-  ObjectFetchContext& getFetchContext() {
+  StatsFetchContext& getFetchContext() {
     return fetchContext_;
   }
 
@@ -85,7 +85,7 @@ class DiffContext {
   std::unique_ptr<TopLevelIgnores> topLevelIgnores_;
   const LoadFileFunction loadFileContentsFromPath_;
   apache::thrift::ResponseChannelRequest* const FOLLY_NULLABLE request_;
-  ObjectFetchContext fetchContext_;
+  StatsFetchContext fetchContext_;
 };
 } // namespace eden
 } // namespace facebook

eden/fs/store/IObjectStore.h

@@ -35,7 +35,7 @@ class ObjectFetchContext {
    *
    * Suitable for use as an index into an array of size kObjectTypeEnumMax
    */
-  enum ObjectType {
+  enum ObjectType : unsigned {
     Blob,
     BlobMetadata,
     Tree,
@@ -47,7 +47,7 @@ class ObjectFetchContext {
    *
    * Suitable for use as an index into an array of size kOriginEnumMax.
    */
-  enum Origin {
+  enum Origin : unsigned {
     FromMemoryCache,
     FromDiskCache,
     FromBackingStore,

eden/fs/store/StatsFetchContext.cpp

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This software may be used and distributed according to the terms of the
+ * GNU General Public License version 2.
+ */
+
+#include "eden/fs/store/StatsFetchContext.h"
+#include <folly/logging/xlog.h>
+
+namespace facebook {
+namespace eden {
+
+StatsFetchContext::StatsFetchContext(const StatsFetchContext& other) {
+  for (size_t y = 0; y < ObjectFetchContext::kObjectTypeEnumMax; ++y) {
+    for (size_t x = 0; x < ObjectFetchContext::kOriginEnumMax; ++x) {
+      // This could almost certainly use a more relaxed memory ordering.
+      counts_[y][x] = other.counts_[y][x].load();
+    }
+  }
+}
+
+void StatsFetchContext::didFetch(ObjectType type, const Hash&, Origin origin) {
+  XCHECK(type < ObjectFetchContext::kObjectTypeEnumMax)
+      << "type is out of range: " << type;
+  XCHECK(origin < ObjectFetchContext::kOriginEnumMax)
+      << "origin is out of range: " << type;
+  counts_[type][origin].fetch_add(1, std::memory_order_acq_rel);
+}
+
+uint64_t StatsFetchContext::countFetchesOfType(ObjectType type) const {
+  XCHECK(type < ObjectFetchContext::kObjectTypeEnumMax)
+      << "type is out of range: " << type;
+  uint64_t result = 0;
+  for (unsigned origin = 0; origin < ObjectFetchContext::kOriginEnumMax;
+       ++origin) {
+    result += counts_[type][origin].load(std::memory_order_acquire);
+  }
+  return result;
+}
+
+void StatsFetchContext::merge(const StatsFetchContext& other) {
+  for (unsigned type = 0; type < ObjectFetchContext::kObjectTypeEnumMax;
+       ++type) {
+    for (unsigned origin = 0; origin < ObjectFetchContext::kOriginEnumMax;
+         ++origin) {
+      counts_[type][origin] += other.counts_[type][origin];
+    }
+  }
+}
+
+} // namespace eden
+} // namespace facebook

eden/fs/store/StatsFetchContext.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This software may be used and distributed according to the terms of the
+ * GNU General Public License version 2.
+ */
+
+#pragma once
+
+#include <atomic>
+#include "eden/fs/store/IObjectStore.h"
+
+namespace facebook {
+namespace eden {
+
+class StatsFetchContext : public ObjectFetchContext {
+ public:
+  StatsFetchContext() = default;
+  StatsFetchContext(const StatsFetchContext& other);
+
+  void didFetch(ObjectType type, const Hash& id, Origin origin) override;
+
+  uint64_t countFetchesOfType(ObjectType type) const;
+
+  /**
+   * Sums the counts from another fetch context into this one.
+   */
+  void merge(const StatsFetchContext& other);
+
+ private:
+  std::atomic<uint64_t> counts_[ObjectFetchContext::kObjectTypeEnumMax]
+                               [ObjectFetchContext::kOriginEnumMax] = {};
+};
+
+} // namespace eden
+} // namespace facebook