live debug journal command

Summary: Running `eden debug journal -f` will print and follow the eden journal in a similar style to the unix `tail -f` command.

Reviewed By: chadaustin

Differential Revision: D16112458

fbshipit-source-id: 5304cd0f857bdbeca41c2591e98920f4f1fc8f42

eden/cli/debug.py

@@ -15,6 +15,7 @@ import shlex
 import shutil
 import stat
 import sys
+import time
 from pathlib import Path
 from typing import (
     IO,
@@ -884,7 +885,7 @@ class DebugJournalGetMemoryLimitCmd(Subcmd):
             return 0
 
 
-@debug_cmd("journal", "Prints the most recent N entries from the journal")
+@debug_cmd("journal", "Prints the most recent entries from the journal")
 class DebugJournalCmd(Subcmd):
     def setup_parser(self, parser: argparse.ArgumentParser) -> None:
         parser.add_argument(
@@ -901,6 +902,13 @@ class DebugJournalCmd(Subcmd):
             help="Show only deltas for paths matching this pattern. "
             "Specify '^((?!^\\.hg/).)*$' to exclude the .hg/ directory.",
         )
+        parser.add_argument(
+            "-f",
+            "--follow",
+            action="store_true",
+            default=False,
+            help="Output appended data as the journal grows.",
+        )
         parser.add_argument(
             "-i",
             "--ignore-case",
@@ -915,27 +923,48 @@ class DebugJournalCmd(Subcmd):
         )
 
     def run(self, args: argparse.Namespace) -> int:
-        instance, checkout, _rel_path = cmd_util.require_checkout(args, args.path)
+        pattern: Optional[Pattern[bytes]] = None
+        if args.pattern:
+            pattern_bytes = args.pattern.encode("utf-8")
+            flags = re.IGNORECASE if args.ignore_case else 0
+            pattern = re.compile(pattern_bytes, flags)
 
+        instance, checkout, _ = cmd_util.require_checkout(args, args.path)
+        mount = bytes(checkout.path)
+
+        def refresh(params):
             with instance.get_thrift_client() as client:
-            params = DebugGetRawJournalParams(
-                mountPoint=bytes(checkout.path), limit=args.limit
-            )
+                journal = client.debugGetRawJournal(params)
+
+            deltas = journal.allDeltas
+            if len(deltas) == 0:
+                seq_num = params.fromSequenceNumber
+            else:
+                seq_num = deltas[0].fromPosition.sequenceNumber + 1
+                _print_raw_journal_deltas(reversed(deltas), pattern)
+
+            return seq_num
+
         try:
-                raw_journal = client.debugGetRawJournal(params)
+            params = DebugGetRawJournalParams(
+                mountPoint=mount, fromSequenceNumber=1, limit=args.limit
+            )
+            seq_num = refresh(params)
+            while args.follow:
+                REFRESH_SEC = 2
+                time.sleep(REFRESH_SEC)
+                params = DebugGetRawJournalParams(
+                    mountPoint=mount, fromSequenceNumber=seq_num
+                )
+                seq_num = refresh(params)
         except EdenError as err:
             print(err, file=sys.stderr)
             return 1
-            if args.pattern:
-                flags = re.IGNORECASE if args.ignore_case else 0
-                bytes_pattern = args.pattern.encode("utf-8")
-                pattern: Optional[Pattern[bytes]] = re.compile(bytes_pattern, flags)
+        except KeyboardInterrupt:
+            if args.follow:
+                pass
             else:
-                pattern = None
-            # debugGetRawJournal() returns the most recent entries first, but
-            # we want to display the oldest entries first, so we pass a reversed
-            # iterator along.
-            _print_raw_journal_deltas(reversed(raw_journal.allDeltas), pattern)
+                raise
 
         return 0
 

eden/fs/journal/Journal.cpp

@@ -224,12 +224,13 @@ std::unique_ptr<JournalDeltaRange> Journal::accumulateRange(
 }
 
 std::vector<DebugJournalDelta> Journal::getDebugRawJournalInfo(
-    size_t limit,
+    SequenceNumber from,
+    std::optional<size_t> limit,
     long mountGeneration) const {
   auto result = std::vector<DebugJournalDelta>();
   forEachDelta(
-      0,
-      std::optional<size_t>(limit),
+      from,
+      limit,
       [mountGeneration, &result](const JournalDelta& current) -> void {
         DebugJournalDelta delta;
         JournalPosition fromPosition;

eden/fs/journal/Journal.h

@@ -144,7 +144,8 @@ class Journal {
    * reached then it will just return what had been currently found.
    * */
   std::vector<DebugJournalDelta> getDebugRawJournalInfo(
-      size_t limit,
+      SequenceNumber from,
+      std::optional<size_t> limit,
       long mountGeneration) const;
 
   void setMemoryLimit(size_t limit);

eden/fs/journal/test/JournalTest.cpp

@@ -138,7 +138,7 @@ TEST(Journal, debugRawJournalInfoRemoveCreateUpdate) {
 
   long mountGen = 333;
 
-  auto debugDeltas = journal.getDebugRawJournalInfo(3, mountGen);
+  auto debugDeltas = journal.getDebugRawJournalInfo(0, 3, mountGen);
   ASSERT_EQ(3, debugDeltas.size());
 
   // Debug Raw Journal Info returns info from newest->latest
@@ -155,14 +155,14 @@ TEST(Journal, debugRawJournalInfoRemoveCreateUpdate) {
   EXPECT_EQ(debugDeltas[2].fromPosition.mountGeneration, mountGen);
   EXPECT_EQ(debugDeltas[2].fromPosition.sequenceNumber, 1);
 
-  debugDeltas = journal.getDebugRawJournalInfo(1, mountGen);
+  debugDeltas = journal.getDebugRawJournalInfo(0, 1, mountGen);
   ASSERT_EQ(1, debugDeltas.size());
   EXPECT_TRUE(debugDeltas[0].changedPaths["test.txt"].existedBefore);
   EXPECT_TRUE(debugDeltas[0].changedPaths["test.txt"].existedAfter);
   EXPECT_EQ(debugDeltas[0].fromPosition.mountGeneration, mountGen);
   EXPECT_EQ(debugDeltas[0].fromPosition.sequenceNumber, 3);
 
-  debugDeltas = journal.getDebugRawJournalInfo(0, mountGen);
+  debugDeltas = journal.getDebugRawJournalInfo(0, 0, mountGen);
   ASSERT_EQ(0, debugDeltas.size());
 }
 

eden/fs/service/EdenServiceHandler.cpp

@@ -675,8 +675,14 @@ void EdenServiceHandler::debugGetRawJournal(
   auto helper = INSTRUMENT_THRIFT_CALL(DBG3, params->mountPoint);
   auto edenMount = server_->getMount(params->mountPoint);
   auto mountGeneration = static_cast<ssize_t>(edenMount->getMountGeneration());
+
+  std::optional<size_t> limitopt = std::nullopt;
+  if (auto limit = params->limit_ref()) {
+    limitopt = static_cast<size_t>(*limit);
+  }
+
   out.allDeltas = edenMount->getJournal().getDebugRawJournalInfo(
-      static_cast<size_t>(params->limit), mountGeneration);
+      params->fromSequenceNumber, limitopt, mountGeneration);
 #else
   NOT_IMPLEMENTED();
 #endif // !_WIN32

eden/fs/service/eden.thrift

@@ -200,7 +200,8 @@ struct FileDelta {
 
 struct DebugGetRawJournalParams {
   1: PathString mountPoint
-  2: i32 limit
+  2: optional i32 limit
+  3: i32 fromSequenceNumber
 }
 
 struct DebugPathChangeInfo {