From 3adf32e361332b9207a627a9f8d19a57d970f4f0 Mon Sep 17 00:00:00 2001
From: Henning Baldersheim <balder@yahoo-inc.com>
Date: Fri, 11 Feb 2022 13:07:40 +0000
Subject: - Use an unordered map. - Add clarifying comments. - Cap mmaplimit in
 the range [1M, 1G].

---
 vespamalloc/src/vespamalloc/malloc/mmappool.h     |  4 ++--
 vespamalloc/src/vespamalloc/malloc/threadpool.hpp | 17 +++++++++++++----
 2 files changed, 15 insertions(+), 6 deletions(-)

(limited to 'vespamalloc')

diff --git a/vespamalloc/src/vespamalloc/malloc/mmappool.h b/vespamalloc/src/vespamalloc/malloc/mmappool.h
index 32c00167c71..c07ef9dce15 100644
--- a/vespamalloc/src/vespamalloc/malloc/mmappool.h
+++ b/vespamalloc/src/vespamalloc/malloc/mmappool.h
@@ -2,7 +2,7 @@
 #pragma once
 
 #include <atomic>
-#include <map>
+#include <unordered_map>
 
 namespace vespamalloc {
 
@@ -27,7 +27,7 @@ private:
     std::atomic<size_t> _count;
     std::atomic<bool>   _has_hugepage_failure_just_happened;
     mutable std::mutex  _mutex;
-    std::map<const void *, MMapInfo> _mappings;
+    std::unordered_map<const void *, MMapInfo> _mappings;
 };
 
 }
diff --git a/vespamalloc/src/vespamalloc/malloc/threadpool.hpp b/vespamalloc/src/vespamalloc/malloc/threadpool.hpp
index 202a6529c99..31ed1296a9e 100644
--- a/vespamalloc/src/vespamalloc/malloc/threadpool.hpp
+++ b/vespamalloc/src/vespamalloc/malloc/threadpool.hpp
@@ -6,11 +6,17 @@
 
 namespace vespamalloc {
 
+namespace {
+    constexpr size_t MMAP_LIMIT_MIN = 0x100000; // 1M
+    constexpr size_t MMAP_LIMIT_MAX = 0x40000000; // 1G
+}
+
 template <typename MemBlockPtrT, typename ThreadStatT>
 size_t ThreadPoolT<MemBlockPtrT, ThreadStatT>::_threadCacheLimit __attribute__((visibility("hidden"))) = 0x10000;
 
 template <typename MemBlockPtrT, typename ThreadStatT>
-void ThreadPoolT<MemBlockPtrT, ThreadStatT>::info(FILE * os, size_t level, const DataSegment<MemBlockPtrT> & ds) const {
+void
+ThreadPoolT<MemBlockPtrT, ThreadStatT>::info(FILE * os, size_t level, const DataSegment<MemBlockPtrT> & ds) const {
     if (level > 0) {
         for (size_t i=0; i < NELEMS(_stat); i++) {
             const ThreadStatT & s = _stat[i];
@@ -50,7 +56,8 @@ void ThreadPoolT<MemBlockPtrT, ThreadStatT>::info(FILE * os, size_t level, const
 }
 
 template <typename MemBlockPtrT, typename ThreadStatT >
-void ThreadPoolT<MemBlockPtrT, ThreadStatT>::
+void
+ThreadPoolT<MemBlockPtrT, ThreadStatT>::
 mallocHelper(size_t exactSize,
              SizeClassT sc,
              typename ThreadPoolT<MemBlockPtrT, ThreadStatT>::AllocFree & af,
@@ -73,6 +80,7 @@ mallocHelper(size_t exactSize,
         } else {
             if (exactSize > _mmapLimit) {
                 mem = MemBlockPtrT(_mmapPool->mmap(MemBlockPtrT::classSize(sc)), MemBlockPtrT::classSize(sc));
+                // The below settings are to allow the sanity checks conducted at the call site to succeed
                 mem.setExact(exactSize);
                 mem.free();
             } else {
@@ -93,7 +101,7 @@ template <typename MemBlockPtrT, typename ThreadStatT >
 ThreadPoolT<MemBlockPtrT, ThreadStatT>::ThreadPoolT() :
     _allocPool(nullptr),
     _mmapPool(nullptr),
-    _mmapLimit(0x40000000),
+    _mmapLimit(MMAP_LIMIT_MAX),
     _threadId(0),
     _osThreadId(0)
 {
@@ -104,8 +112,9 @@ ThreadPoolT<MemBlockPtrT, ThreadStatT>::~ThreadPoolT() = default;
 
 template <typename MemBlockPtrT, typename ThreadStatT >
 int ThreadPoolT<MemBlockPtrT, ThreadStatT>::mallopt(int param, int value) {
+    size_t limit = value;
     if (param == M_MMAP_THRESHOLD) {
-        _mmapLimit = value;
+        _mmapLimit = std::min(MMAP_LIMIT_MAX, std::max(MMAP_LIMIT_MIN, limit));
         return 1;
     }
     return 0;
-- 
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