From 6f38a6a711ea0eec2914d8119a676bb8d8a185ba Mon Sep 17 00:00:00 2001
From: Dmitriy Musatkin <musatkd@amazon.com>
Date: Fri, 20 Oct 2023 16:21:58 -0700
Subject: [PATCH] doc

---
 include/aws/common/system_resource_util.h | 12 ++++++++----
 source/posix/system_resource_utils.c      | 13 +++++++++----
 source/windows/system_resource_utils.c    | 10 +++++-----
 tests/CMakeLists.txt                      |  2 +-
 tests/system_resource_util_test.c         | 12 ++++++------
 5 files changed, 29 insertions(+), 20 deletions(-)

diff --git a/include/aws/common/system_resource_util.h b/include/aws/common/system_resource_util.h
index df1c456bc..a4a8e4860 100644
--- a/include/aws/common/system_resource_util.h
+++ b/include/aws/common/system_resource_util.h
@@ -11,14 +11,18 @@ AWS_PUSH_SANE_WARNING_LEVEL
 
 AWS_EXTERN_C_BEGIN
 
-struct aws_resource_usage {
-    size_t maxrss;
-    size_t page_faults;
+struct aws_memory_usage {
+    size_t maxrss; /* max resident set size in kilobytes since program start */
+    size_t page_faults; /* num of page faults since program start */
 
     size_t _reserved[8];
 };
 
-AWS_COMMON_API int aws_resource_usage_for_current_process(struct aws_resource_usage *resource_usage);
+/*
+ * Get memory usage for current process.
+ * Raises AWS_ERROR_SYS_CALL_FAILURE on failure.
+*/
+AWS_COMMON_API int aws_memory_usage_for_current_process(struct aws_memory_usage *memory_usage);
 
 AWS_EXTERN_C_END
 AWS_POP_SANE_WARNING_LEVEL
diff --git a/source/posix/system_resource_utils.c b/source/posix/system_resource_utils.c
index cc2774643..7863013bb 100644
--- a/source/posix/system_resource_utils.c
+++ b/source/posix/system_resource_utils.c
@@ -7,8 +7,8 @@
 
 #include <sys/resource.h>
 
-int aws_resource_usage_for_current_process(struct aws_resource_usage *ru) {
-    AWS_PRECONDITION(ru);
+int aws_memory_usage_for_current_process(struct aws_memory_usage *mu) {
+    AWS_PRECONDITION(mu);
 
     struct rusage usage;
 
@@ -17,9 +17,14 @@ int aws_resource_usage_for_current_process(struct aws_resource_usage *ru) {
     }
 
 #if defined(AWS_OS_APPLE)
-    ru->maxrss = usage.ru_maxrss / 1024;
+    /*
+    * For some reason Apple switched to reporting this in bytes instead of KB
+    * around MacOS 10.6. 
+    * Make it back to KB. Result might be slightly off due to rounding.
+    */
+    mu->maxrss = usage.ru_maxrss / 1024;
 #else
-    ru->maxrss = usage.ru_maxrss;
+    mu->maxrss = usage.ru_maxrss;
 #endif
     ru->page_faults = usage.ru_majflt;
     return AWS_OP_SUCCESS;
diff --git a/source/windows/system_resource_utils.c b/source/windows/system_resource_utils.c
index 1d63fe701..847ccef94 100644
--- a/source/windows/system_resource_utils.c
+++ b/source/windows/system_resource_utils.c
@@ -10,11 +10,11 @@
 #include <psapi.h>
 
 
-int aws_resource_usage_for_current_process(struct aws_resource_usage *ru) {
-    AWS_PRECONDITION(resource_usage);
+int aws_memory_usage_for_current_process(struct aws_memory_usage *mu) {
+    AWS_PRECONDITION(mu);
 
     HANDLE hProcess = GetCurrentProcess();
-    ;
+    
     PROCESS_MEMORY_COUNTERS pmc;
 
     BOOL ret = GetProcessMemoryInfo(hProcess, &pmc, sizeof(pmc));
@@ -24,8 +24,8 @@ int aws_resource_usage_for_current_process(struct aws_resource_usage *ru) {
         return aws_raise_error(AWS_ERROR_SYS_CALL_FAILURE);
     }
 
-    ru->maxrss = pmc.PeakWorkingSetSize;
-    ru->page_faults = pmc.PageFaultCount;
+    mu->maxrss = pmc.PeakWorkingSetSize;
+    mu->page_faults = pmc.PageFaultCount;
 
     return AWS_OP_SUCCESS;
 }
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 907432b58..de072868a 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -402,7 +402,7 @@ add_test_case(ring_buffer_acquire_up_to_multi_threaded_test)
 add_test_case(string_to_log_level_success_test)
 add_test_case(string_to_log_level_failure_test)
 
-add_test_case(test_resource_usage_maxrss)
+add_test_case(test_memory_usage_maxrss)
 
 if(NOT ANDROID)
     add_test_case(test_logging_filter_at_AWS_LL_NONE_s_logf_all_levels)
diff --git a/tests/system_resource_util_test.c b/tests/system_resource_util_test.c
index f89c79a8f..0d58882d8 100644
--- a/tests/system_resource_util_test.c
+++ b/tests/system_resource_util_test.c
@@ -7,17 +7,17 @@
 
 #include <aws/testing/aws_test_harness.h>
 
-static int s_test_resource_usage_maxrss(struct aws_allocator *allocator, void *ctx) {
+static int s_test_memory_usage_maxrss(struct aws_allocator *allocator, void *ctx) {
     (void)allocator;
     (void)ctx;
 
-    struct aws_resource_usage ru;
-    AWS_ZERO_STRUCT(ru);
-    ASSERT_SUCCESS(aws_resource_usage_for_current_process(&ru));
+    struct aws_resource_usage mu;
+    AWS_ZERO_STRUCT(mu);
+    ASSERT_SUCCESS(aws_memory_usage_for_current_process(&mu));
 
-    ASSERT_TRUE(ru.maxrss > 0);
+    ASSERT_TRUE(mu.maxrss > 0);
 
     return 0;
 }
 
-AWS_TEST_CASE(test_resource_usage_maxrss, s_test_resource_usage_maxrss)
\ No newline at end of file
+AWS_TEST_CASE(test_memory_usage_maxrss, s_test_memory_usage_maxrss)
\ No newline at end of file