From f41cc87088c502c3837567a563c44eb752f8c0d6 Mon Sep 17 00:00:00 2001
From: Ozan Tezcan <ozantezcan@gmail.com>
Date: Thu, 13 Jan 2022 12:36:03 +0300
Subject: [PATCH] Added RM_MonotonicMicroseconds() API to provide monotonic
 time function (#10101)

Added RM_MonotonicMicroseconds(). Modules can use monotonic timestamp counter for measurements.
---
 src/module.c                  |  6 ++++++
 src/redismodule.h             |  2 ++
 tests/modules/misc.c          | 10 ++++++++++
 tests/unit/moduleapi/misc.tcl |  5 +++++
 4 files changed, 23 insertions(+)

diff --git a/src/module.c b/src/module.c
index 6cc9c2b0e..90ea2df7d 100644
--- a/src/module.c
+++ b/src/module.c
@@ -1326,6 +1326,11 @@ long long RM_Milliseconds(void) {
     return mstime();
 }
 
+/* Return counter of micro-seconds relative to an arbitrary point in time. */
+uint64_t RM_MonotonicMicroseconds(void) {
+    return getMonotonicUs();
+}
+
 /* Mark a point in time that will be used as the start time to calculate
  * the elapsed execution time when RM_BlockedClientMeasureTimeEnd() is called.
  * Within the same command, you can call multiple times
@@ -10599,6 +10604,7 @@ void moduleRegisterCoreAPI(void) {
     REGISTER_API(GetBlockedClientPrivateData);
     REGISTER_API(AbortBlock);
     REGISTER_API(Milliseconds);
+    REGISTER_API(MonotonicMicroseconds);
     REGISTER_API(BlockedClientMeasureTimeStart);
     REGISTER_API(BlockedClientMeasureTimeEnd);
     REGISTER_API(GetThreadSafeContext);
diff --git a/src/redismodule.h b/src/redismodule.h
index 0f8ab6fb2..4ce342338 100644
--- a/src/redismodule.h
+++ b/src/redismodule.h
@@ -837,6 +837,7 @@ REDISMODULE_API int (*RedisModule_GetToDbIdFromOptCtx)(RedisModuleKeyOptCtx *ctx
 REDISMODULE_API const RedisModuleString * (*RedisModule_GetKeyNameFromOptCtx)(RedisModuleKeyOptCtx *ctx) REDISMODULE_ATTR;
 REDISMODULE_API const RedisModuleString * (*RedisModule_GetToKeyNameFromOptCtx)(RedisModuleKeyOptCtx *ctx) REDISMODULE_ATTR;
 REDISMODULE_API long long (*RedisModule_Milliseconds)(void) REDISMODULE_ATTR;
+REDISMODULE_API uint64_t (*RedisModule_MonotonicMicroseconds)(void) REDISMODULE_ATTR;
 REDISMODULE_API void (*RedisModule_DigestAddStringBuffer)(RedisModuleDigest *md, unsigned char *ele, size_t len) REDISMODULE_ATTR;
 REDISMODULE_API void (*RedisModule_DigestAddLongLong)(RedisModuleDigest *md, long long ele) REDISMODULE_ATTR;
 REDISMODULE_API void (*RedisModule_DigestEndSequence)(RedisModuleDigest *md) REDISMODULE_ATTR;
@@ -1154,6 +1155,7 @@ static int RedisModule_Init(RedisModuleCtx *ctx, const char *name, int ver, int
     REDISMODULE_GET_API(GetDbIdFromOptCtx);
     REDISMODULE_GET_API(GetToDbIdFromOptCtx);
     REDISMODULE_GET_API(Milliseconds);
+    REDISMODULE_GET_API(MonotonicMicroseconds);
     REDISMODULE_GET_API(DigestAddStringBuffer);
     REDISMODULE_GET_API(DigestAddLongLong);
     REDISMODULE_GET_API(DigestEndSequence);
diff --git a/tests/modules/misc.c b/tests/modules/misc.c
index 94b4754ad..db9c090d4 100644
--- a/tests/modules/misc.c
+++ b/tests/modules/misc.c
@@ -302,6 +302,14 @@ int test_weird_cmd(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
     return REDISMODULE_OK;
 }
 
+int test_monotonic_time(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    REDISMODULE_NOT_USED(argv);
+    REDISMODULE_NOT_USED(argc);
+
+    RedisModule_ReplyWithLongLong(ctx, RedisModule_MonotonicMicroseconds());
+    return REDISMODULE_OK;
+}
+
 int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
     REDISMODULE_NOT_USED(argv);
     REDISMODULE_NOT_USED(argc);
@@ -341,6 +349,8 @@ int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
     /* Add a command with ':' in it's name, so that we can check commandstats sanitization. */
     if (RedisModule_CreateCommand(ctx,"test.weird:cmd", test_weird_cmd,"readonly",0,0,0) == REDISMODULE_ERR)
         return REDISMODULE_ERR;
+    if (RedisModule_CreateCommand(ctx,"test.monotonic_time", test_monotonic_time,"",0,0,0) == REDISMODULE_ERR)
+        return REDISMODULE_ERR;
 
     return REDISMODULE_OK;
 }
diff --git a/tests/unit/moduleapi/misc.tcl b/tests/unit/moduleapi/misc.tcl
index 091de4a87..9aa191814 100644
--- a/tests/unit/moduleapi/misc.tcl
+++ b/tests/unit/moduleapi/misc.tcl
@@ -128,4 +128,9 @@ start_server {tags {"modules"}} {
         set info [r info commandstats]
         assert_match {*cmdstat_test.weird_cmd:calls=1*} $info
     }
+
+    test {test monotonic time} {
+        set x [r test.monotonic_time]
+        assert { [r test.monotonic_time] >= $x }
+    }
 }