Add a method to get the system's page size

2 files changed, 57 insertions, 0 deletions

diff --git a/common/almalloc.c b/common/almalloc.c
index 8c1c5794..0d982ca1 100644
--- a/common/almalloc.c
+++ b/common/almalloc.c
@@ -10,8 +10,20 @@
 #endif
 #ifdef HAVE_WINDOWS_H
 #include <windows.h>
+#else
+#include <unistd.h>
+#endif
+
+
+#ifdef __GNUC__
+#define LIKELY(x) __builtin_expect(!!(x), !0)
+#define UNLIKELY(x) __builtin_expect(!!(x), 0)
+#else
+#define LIKELY(x) (!!(x))
+#define UNLIKELY(x) (!!(x))
 #endif
 
+
 void *al_malloc(size_t alignment, size_t size)
 {
 #if defined(HAVE_ALIGNED_ALLOC)
@@ -60,3 +72,39 @@ void al_free(void *ptr)
     }
 #endif
 }
+
+size_t al_get_page_size(void)
+{
+    static size_t psize = 0;
+    if(UNLIKELY(!psize))
+    {
+#ifdef HAVE_SYSCONF
+#if defined(_SC_PAGESIZE)
+        if(!psize) psize = sysconf(_SC_PAGESIZE);
+#elif defined(_SC_PAGE_SIZE)
+        if(!psize) psize = sysconf(_SC_PAGE_SIZE);
+#endif
+#endif /* HAVE_SYSCONF */
+#ifdef _WIN32
+        if(!psize)
+        {
+            SYSTEM_INFO sysinfo;
+            memset(&sysinfo, 0, sizeof(sysinfo));
+
+            GetSystemInfo(&sysinfo);
+            psize = sysinfo.dwPageSize;
+        }
+#endif
+        if(!psize) psize = DEF_ALIGN;
+    }
+    return psize;
+}
+
+int al_is_sane_alignment_allocator(void)
+{
+#if defined(HAVE_ALIGNED_ALLOC) || defined(HAVE_POSIX_MEMALIGN) || defined(HAVE__ALIGNED_MALLOC)
+    return 1;
+#else
+    return 0;
+#endif
+}
diff --git a/common/almalloc.h b/common/almalloc.h
index 8eadb5b3..a4297cf5 100644
--- a/common/almalloc.h
+++ b/common/almalloc.h
@@ -14,6 +14,15 @@ void *al_malloc(size_t alignment, size_t size);
 void *al_calloc(size_t alignment, size_t size);
 void al_free(void *ptr);
 
+size_t al_get_page_size(void);
+
+/**
+ * Returns non-0 if the allocation function has direct alignment handling.
+ * Otherwise, the standard malloc is used with an over-allocation and pointer
+ * offset strategy.
+ */
+int al_is_sane_alignment_allocator(void);
+
 #ifdef __cplusplus
 }
 #endif