SERVER-48742 Log changes to profiler settings

(cherry picked from commit 0d30729722165f15e52db2c02ebb56cfd1c6ccc1)

2 files changed, 65 insertions, 11 deletions

diff --git a/jstests/core/apitest_db_profile_level.js b/jstests/core/apitest_db_profile_level.js
index adfc2b0ee43..d72e7e39f02 100644
--- a/jstests/core/apitest_db_profile_level.js
+++ b/jstests/core/apitest_db_profile_level.js
@@ -1,11 +1,13 @@
 /**
  *  Tests for setting of profile levels
- *  @tags: [does_not_support_stepdowns, requires_profiling]
+ *  @tags: [does_not_support_stepdowns, requires_profiling, requires_fcv_42]
  */
 
 (function() {
 'use strict';
 
+load("jstests/libs/log.js");  // For findMatchingLogLine, findMatchingLogLines.
+
 /*
  *  be sure the public collection API is complete
  */
@@ -16,25 +18,51 @@ assert(db.setProfilingLevel, "setProfilingLevel");
 // other tests that modify profiler level, when run in parallel.
 var profileLevelDB = db.getSiblingDB("apitest_db_profile_level");
 
+// Checks for the log that was expected to be created when profile level changed.
+function profilerChangeWasLogged({from, to} = {}) {
+    const globalLog = assert.commandWorked(profileLevelDB.adminCommand({getLog: 'global'}));
+
+    const fieldMatcher = {msg: "Profiler settings changed"};
+    if (from && to) {
+        const lines = [...findMatchingLogLines(globalLog.log, fieldMatcher)];
+        return lines.find(line => line.match(new RegExp(/"from":{/.source + from.source)) &&
+                              line.match(new RegExp(/"to":{/.source + to.source)));
+    } else {
+        return findMatchingLogLine(globalLog.log, fieldMatcher);
+    }
+}
+
+profileLevelDB.getProfilingLevel();
+assert(!profilerChangeWasLogged({from: /"level":0/, to: /"level":-1/}),
+       "Didn't expect anything to be logged");
+
+assert.throws(() => {
+    profileLevelDB.setProfilingLevel(-1);
+});
+
 profileLevelDB.setProfilingLevel(0);
 assert(profileLevelDB.getProfilingLevel() == 0, "prof level 0");
+assert(profilerChangeWasLogged({from: /"level":0/, to: /"level":0/}),
+       "Didn't find expected log line");
 
 profileLevelDB.setProfilingLevel(1);
 assert(profileLevelDB.getProfilingLevel() == 1, "p1");
+assert(profilerChangeWasLogged({from: /"level":0/, to: /"level":1/}),
+       "Didn't find expected log line");
 
 profileLevelDB.setProfilingLevel(2);
 assert(profileLevelDB.getProfilingLevel() == 2, "p2");
+assert(profilerChangeWasLogged({from: /"level":1/, to: /"level":2/}),
+       "Didn't find expected log line");
 
 profileLevelDB.setProfilingLevel(0);
 assert(profileLevelDB.getProfilingLevel() == 0, "prof level 0");
+assert(profilerChangeWasLogged({from: /"level":2/, to: /"level":0/}),
+       "Didn't find expected log line");
 
-var asserted = false;
-try {
+assert.throws(() => {
     profileLevelDB.setProfilingLevel(10);
-    assert(false);
-} catch (e) {
-    asserted = true;
-    assert(e.dbSetProfilingException);
-}
-assert(asserted, "should have asserted");
+});
+// Check that didn't log an invalid profile level change.
+assert(!profilerChangeWasLogged({from: /"level":0/, to: /"level":10/}), "Didn't expect log line");
 })();
diff --git a/src/mongo/db/commands/profile_common.cpp b/src/mongo/db/commands/profile_common.cpp
index bfb095630eb..1691848ee72 100644
--- a/src/mongo/db/commands/profile_common.cpp
+++ b/src/mongo/db/commands/profile_common.cpp
@@ -26,13 +26,16 @@
  *    exception statement from all source files in the program, then also delete
  *    it in the license file.
  */
+#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kCommand
 
 #include "mongo/platform/basic.h"
 
 #include "mongo/db/auth/authorization_session.h"
 #include "mongo/db/commands/profile_common.h"
 #include "mongo/db/commands/profile_gen.h"
+#include "mongo/db/jsobj.h"
 #include "mongo/idl/idl_parser.h"
+#include "mongo/util/log.h"
 
 namespace mongo {
 
@@ -69,10 +72,12 @@ bool ProfileCmdBase::run(OperationContext* opCtx,
     // Delegate to _applyProfilingLevel to set the profiling level appropriately whether we are on
     // mongoD or mongoS.
     int oldLevel = _applyProfilingLevel(opCtx, dbName, profilingLevel);
+    auto oldSlowMS = serverGlobalParams.slowMS;
+    auto oldSampleRate = serverGlobalParams.sampleRate;
 
     result.append("was", oldLevel);
-    result.append("slowms", serverGlobalParams.slowMS);
-    result.append("sampleRate", serverGlobalParams.sampleRate);
+    result.append("slowms", oldSlowMS);
+    result.append("sampleRate", oldSampleRate);
 
     if (auto slowms = request.getSlowms()) {
         serverGlobalParams.slowMS = *slowms;
@@ -84,6 +89,27 @@ bool ProfileCmdBase::run(OperationContext* opCtx,
         serverGlobalParams.sampleRate = *sampleRate;
     }
 
+    // Log the change made to server's profiling settings, unless the request was to get the current
+    // value.
+    if (profilingLevel != -1) {
+        logv2::DynamicAttributes attrs;
+
+        BSONObjBuilder oldState;
+        BSONObjBuilder newState;
+
+        oldState.append("level"_sd, oldLevel);
+        oldState.append("slowms"_sd, oldSlowMS);
+        oldState.append("sampleRate"_sd, oldSampleRate);
+        attrs.add("from", oldState.obj());
+
+        newState.append("level"_sd, profilingLevel);
+        newState.append("slowms"_sd, serverGlobalParams.slowMS);
+        newState.append("sampleRate"_sd, serverGlobalParams.sampleRate);
+        attrs.add("to", newState.obj());
+
+        LOGV2(48742, "Profiler settings changed", attrs);
+    }
+
     return true;
 }
 }  // namespace mongo