on behalf of marklalon from (https://github.com/marklalon/UnityAndroidIl2cppPatchDemo-libboostrap)

1. spin lock.
2. limited file buffer.

Author: noodle1983

pthread_mutex.hpp

@@ -15,26 +15,29 @@
 
 
 #include <pthread.h>
+#include "pthread_spin_lock.h"
 //#include "log.h"
 
 class PthreadMutex  
 {
 public:
-    PthreadMutex(){pthread_mutex_init(&mutexlock, 0);}
-    virtual ~PthreadMutex(){pthread_mutex_destroy(&mutexlock);}
+    PthreadMutex(){pthread_spin_init(&mutexlock, 0);}
+    virtual ~PthreadMutex(){pthread_spin_destroy(&mutexlock);}
 
     void Lock(){
-		pthread_mutex_lock(&mutexlock);
+		pthread_spin_lock(&mutexlock);
 		//MY_METHOD("lock at mutex: 0x%08llx", (unsigned long long)&mutexlock);
 	}
     void Unlock(){	
 		//MY_METHOD("unlock at mutex: 0x%08llx", (unsigned long long)&mutexlock);
-		pthread_mutex_unlock(&mutexlock);
+		pthread_spin_unlock(&mutexlock);
 	}
 private:
-    pthread_mutex_t mutexlock;
+    pthread_spinlock_t mutexlock;
 };
 
+
+
 typedef PthreadMutex PthreadRwMutex;
 
 class PthreadGuard

pthread_spin_lock.h

@@ -0,0 +1,42 @@
+//
+// Created by lizhen on 2020/11/18.
+//
+
+#ifndef PTHREAD_SPIN_LOCK_SHIM
+#define PTHREAD_SPIN_LOCK_SHIM
+
+#include <errno.h>
+
+typedef int pthread_spinlock_t;
+
+static inline int pthread_spin_init(pthread_spinlock_t *lock, int pshared) {
+	__asm__ __volatile__ ("" ::: "memory");
+	*lock = 0;
+	return 0;
+}
+
+static inline int pthread_spin_destroy(pthread_spinlock_t *lock) {
+	return 0;
+}
+
+static inline int pthread_spin_lock(pthread_spinlock_t *lock) {
+	while (1) {
+        if (__sync_bool_compare_and_swap(lock, 0, 1))
+            return 0;
+	}
+}
+
+static inline int pthread_spin_trylock(pthread_spinlock_t *lock) {
+	if (__sync_bool_compare_and_swap(lock, 0, 1)) {
+		return 0;
+	}
+	return EBUSY;
+}
+
+static inline int pthread_spin_unlock(pthread_spinlock_t *lock) {
+	__asm__ __volatile__ ("" ::: "memory");
+	*lock = 0;
+	return 0;
+}
+
+#endif

push.unittest.cmd

@@ -0,0 +1 @@
+adb push libs/x86/test_pthread_mutex /data/local/tmp/ && adb push libs/x86/test_ashmem /data/local/tmp/ && pause

zip/shadow_zip.cpp

@@ -654,7 +654,8 @@ FILE* ShadowZip::prepare_file(int _file_index)
         return fp_array_[_file_index];
     }
 
-	//incace of too many file opened, close all except base.apk
+	//in cace of too many file opened, close all except base.apk
+	//but if you have only one patch file including everything, you can comment these to get a better performance. The max open files may reach to 100.
 	for(int i = 1; i < fp_array_.size(); i++) 
     {
 		FILE* fp = fp_array_[i];
@@ -674,6 +675,8 @@ FILE* ShadowZip::prepare_file(int _file_index)
 	MY_METHOD("prepare_file %s -> 0x%08zx", path.c_str(), (size_t)fp);
     fp_array_[_file_index] = fp;
 
+	//if you have only one patch file including everything, the reading index can be random each time. a smaller buffer size performs better.
+	//for others, 1024 is also fair enough.
 	setvbuf( fp , NULL , _IOFBF , 1024);
     return fp;
 }