implement getFilesChangedSince

Summary:
This is pretty straightforward; we just walk back until we hit the
boundary with the requested JournalPosition.sequenceNumber

Reviewed By: simpkins

Differential Revision: D3872970

fbshipit-source-id: 1405f05957346d7ac513070f0407a477548aff1d

eden/fs/integration/materialized_query_test.py

@@ -7,10 +7,11 @@
 # LICENSE file in the root directory of this source tree. An additional grant
 # of patent rights can be found in the PATENTS file in the same directory.
 
+import errno
 import os
 import stat
 from .lib import testcase
-
+from facebook.eden import EdenService
 
 @testcase.eden_repo_test
 class MaterializedQueryTest:
@@ -42,9 +43,26 @@ class MaterializedQueryTest:
         self.assertEqual(1, pos.sequenceNumber)
         self.assertNotEqual(0, pos.mountGeneration)
 
-    def test_addFile(self):
+        changed = self.client.getFilesChangedSince(self.mount, pos)
+        self.assertEqual(0, len(changed.paths))
+        self.assertEqual(pos, changed.fromPosition)
+        self.assertEqual(pos, changed.toPosition)
+
+    def test_invalidProcessGeneration(self):
+        # Get a candidate position
         pos = self.client.getCurrentJournalPosition(self.mount)
-        self.assertEqual(1, pos.sequenceNumber)
+
+        # poke the generation to a value that will never manifest in practice
+        pos.mountGeneration = 0
+
+        with self.assertRaises(EdenService.EdenError) as context:
+            self.client.getFilesChangedSince(self.mount, pos)
+        self.assertEqual(errno.ERANGE, context.exception.errorCode,
+                         msg='Must return ERANGE')
+
+    def test_addFile(self):
+        initial_pos = self.client.getCurrentJournalPosition(self.mount)
+        self.assertEqual(1, initial_pos.sequenceNumber)
 
         name = os.path.join(self.mount, 'overlaid')
         with open(name, 'w+') as f:
@@ -52,13 +70,25 @@ class MaterializedQueryTest:
             self.assertEqual(2, pos.sequenceNumber,
                              msg='creating a file bumps the journal')
 
+            changed = self.client.getFilesChangedSince(self.mount, initial_pos)
+            self.assertEqual(['overlaid'], changed.paths)
+            self.assertEqual(initial_pos.sequenceNumber + 1,
+                             changed.fromPosition.sequenceNumber,
+                             msg='changes start AFTER initial_pos')
+
             f.write('NAME!\n')
 
-        pos = self.client.getCurrentJournalPosition(self.mount)
-        self.assertEqual(3, pos.sequenceNumber, msg='writing bumps the journal')
+        pos_after_overlaid = self.client.getCurrentJournalPosition(self.mount)
+        self.assertEqual(3, pos_after_overlaid.sequenceNumber,
+                         msg='writing bumps the journal')
+        changed = self.client.getFilesChangedSince(self.mount, initial_pos)
+        self.assertEqual(['overlaid'], changed.paths)
+        self.assertEqual(initial_pos.sequenceNumber + 1,
+                         changed.fromPosition.sequenceNumber,
+                         msg='changes start AFTER initial_pos')
 
         info = self.client.getMaterializedEntries(self.mount)
-        self.assertEqual(pos, info.currentPosition,
+        self.assertEqual(pos_after_overlaid, info.currentPosition,
                          msg='consistent with getCurrentJournalPosition')
 
         items = info.fileInfo
@@ -81,6 +111,13 @@ class MaterializedQueryTest:
         self.assertEqual(4, pos.sequenceNumber,
                          msg='appending bumps the journal')
 
+        changed = self.client.getFilesChangedSince(
+            self.mount, pos_after_overlaid)
+        self.assertEqual(['adir/file'], changed.paths)
+        self.assertEqual(pos_after_overlaid.sequenceNumber + 1,
+                         changed.fromPosition.sequenceNumber,
+                         msg='changes start AFTER pos_after_overlaid')
+
         info = self.client.getMaterializedEntries(self.mount)
         self.assertEqual(pos, info.currentPosition,
                          msg='consistent with getCurrentJournalPosition')

eden/fs/service/EdenServiceHandler.cpp

@@ -12,6 +12,7 @@
 #include <boost/polymorphic_cast.hpp>
 #include <folly/FileUtil.h>
 #include <folly/String.h>
+#include <unordered_set>
 #include "EdenServer.h"
 #include "eden/fs/config/ClientConfig.h"
 #include "eden/fs/inodes/EdenMount.h"
@@ -328,6 +329,55 @@ void EdenServiceHandler::getCurrentJournalPosition(
   out.snapshotHash = StringPiece(latest->toHash.getBytes()).str();
 }
 
+void EdenServiceHandler::getFilesChangedSince(
+    FileDelta& out,
+    std::unique_ptr<std::string> mountPoint,
+    std::unique_ptr<JournalPosition> fromPosition) {
+  auto edenMount = server_->getMount(*mountPoint);
+  auto inodeDispatcher = edenMount->getMountPoint()->getDispatcher();
+
+  auto delta = edenMount->getJournal().rlock()->getLatest();
+
+  if (fromPosition->mountGeneration != edenMount->getMountGeneration()) {
+    throw EdenError(
+        apache::thrift::FragileConstructor(),
+        "fromPosition.mountGeneration does not match the current "
+        "mountGeneration.  "
+        "You need to compute a new basis for delta queries.",
+        ERANGE);
+  }
+
+  std::unordered_set<RelativePath> changedFiles;
+
+  out.toPosition.sequenceNumber = delta->toSequence;
+  out.toPosition.snapshotHash = StringPiece(delta->toHash.getBytes()).str();
+  out.toPosition.mountGeneration = edenMount->getMountGeneration();
+
+  out.fromPosition = out.toPosition;
+
+  while (delta) {
+    if (delta->toSequence <= fromPosition->sequenceNumber) {
+      // We've reached the end of the interesting section
+      break;
+    }
+
+    changedFiles.insert(
+        delta->changedFilesInOverlay.begin(),
+        delta->changedFilesInOverlay.end());
+
+    out.fromPosition.sequenceNumber = delta->fromSequence;
+    out.fromPosition.snapshotHash =
+        StringPiece(delta->fromHash.getBytes()).str();
+    out.fromPosition.mountGeneration = edenMount->getMountGeneration();
+
+    delta = delta->previous;
+  }
+
+  for (auto& path : changedFiles) {
+    out.paths.emplace_back(path.stringPiece().str());
+  }
+}
+
 void EdenServiceHandler::shutdown() {
   server_->stop();
 }

eden/fs/service/EdenServiceHandler.h

@@ -56,6 +56,11 @@ class EdenServiceHandler : virtual public EdenServiceSvIf,
       JournalPosition& out,
       std::unique_ptr<std::string> mountPoint) override;
 
+  void getFilesChangedSince(
+      FileDelta& out,
+      std::unique_ptr<std::string> mountPoint,
+      std::unique_ptr<JournalPosition> fromPosition) override;
+
   /**
    * When this Thrift handler is notified to shutdown, it notifies the
    * EdenServer to shut down, as well.

eden/fs/service/eden.thrift

@@ -143,6 +143,7 @@ service EdenService extends fb303.FacebookService {
   FileDelta getFilesChangedSince(
     1: string mountPoint,
     2: JournalPosition fromPosition)
+      throws (1: EdenError ex)
 
   /** Returns a subset of the stat() information for a list of paths.
    * The returned list of information corresponds to the input list of