ipv6 supporting for clang

binding/c/Makefile

@@ -1,24 +1,27 @@
-all: xdb_searcher util_test
+all: xdb_searcher test_util
 
-xdb_searcher: xdb_searcher.h xdb_searcher.c main.c
+xdb_searcher: xdb_api.h xdb_util.c xdb_searcher.c main.c
-	gcc -O2 -I./ xdb_searcher.c main.c -o xdb_searcher
+	gcc -O2 -I./ xdb_util.c xdb_searcher.c main.c -o xdb_searcher
 
-util_test: xdb_searcher.h xdb_searcher.c util_test.c
+test_util: xdb_api.h xdb_util.c test_util.c
-	gcc -O2 -I./ xdb_searcher.c util_test.c -o util_test
+	gcc -O2 -I./ xdb_util.c test_util.c -o test_util
 
 xdb_searcher.o: xdb_searcher.c
-	gcc -c -o xdb_searcher.o xdb_searcher.c
+	gcc -c xdb_searcher.c
 
-xdb_searcher_lib: xdb_searcher.o
+xdb_util.o: xdb_util.c
+	gcc -c xdb_util.c
+
+xdb_searcher_lib: xdb_util.o xdb_searcher.o
 	mkdir -p build/lib
 	mkdir -p build/include
-	ar -rc build/lib/libxdb_searcher.a `find . -name *.o`
+	ar -rc build/lib/libxdb.a `find . -name *.o`
-	cp xdb_searcher.h build/include
+	cp xdb_api.h build/include
 
 clean:
 	find ./ -name \*.o  | xargs rm -f
-	find ./ -name util_test | xargs rm -f
+	find ./ -name test_util | xargs rm -f
 	find ./ -name xdb_searcher | xargs rm -f
 	rm -rf build
 
-.PHONY: all clean xdb_searcher util_test
+.PHONY: all clean xdb_searcher test_util

binding/c/ReadMe.md

@@ -7,7 +7,7 @@
 
 ```c
 #include <stdio.h>
-#include "xdb_searcher.h"
+#include "xdb_api.h"
 
 int main(int argc, char *argv[]) {
     char *db_path = "ip2region.xdb file path";
@@ -45,7 +45,7 @@ int main(int argc, char *argv[]) {
 我们可以提前从 xdb 文件中加载出来 VectorIndex 数据，然后全局缓存，每次创建 Searcher 对象的时候使用全局的 VectorIndex 缓存可以减少一次固定的 IO 操作，从而加速查询，减少 IO 压力。
 ```c
 #include <stdio.h>
-#include "xdb_searcher.h"
+#include "xdb_api.h"
 
 int main(int argc, char *argv[]) {
     char *db_path = "ip2region.xdb file path";
@@ -94,7 +94,7 @@ int main(int argc, char *argv[]) {
 我们也可以预先加载整个 ip2region.xdb 的数据到内存，然后基于这个数据创建查询对象来实现完全基于文件的查询，类似之前的 memory search。
 ```c
 #include <stdio.h>
-#include "xdb_searcher.h"
+#include "xdb_api.h"
 
 int main(int argc, char *argv[]) {
     char *db_path = "ip2region.xdb file path";

binding/c/main.c

@@ -7,7 +7,7 @@
 // @Date   2022/06/28
 
 #include "stdio.h"
-#include "xdb_searcher.h"
+#include "xdb_api.h"
 
 struct searcher_test_entry {
     xdb_searcher_t searcher;
@@ -64,13 +64,13 @@ void destroy_searcher_test(searcher_test_t *test) {
 
     // check and free the vector index
     if (test->v_index != NULL) {
-        xdb_close_vector_index(test->v_index);
+        xdb_free_vector_index(test->v_index);
         test->v_index = NULL;
     }
 
     // check and free the content buffer
     if (test->c_buffer != NULL) {
-        xdb_close_content(test->c_buffer);
+        xdb_free_content(test->c_buffer);
         test->c_buffer = NULL;
     }
 }

binding/c/test_util.c

@@ -7,7 +7,7 @@
 // @Date   2022/06/27
 
 #include "stdio.h"
-#include "xdb_searcher.h"
+#include "xdb_api.h"
 
 void test_check_ip() {
     char *ip_list[] = {
@@ -37,7 +37,7 @@ void test_check_ip() {
 }
 
 void test_load_header() {
-    xdb_header_t *header = xdb_load_header_from_file("../../data/ip2region.xdb");
+    xdb_header_t *header = xdb_load_header_from_file("../../data/ip2region_v4.xdb");
     if (header == NULL) {
         printf("failed to load header");
     } else {
@@ -54,29 +54,29 @@ void test_load_header() {
        );
     }
 
-    xdb_close_header(header);
+    xdb_free_header(header);
 }
 
 void test_load_vector_index() {
-    xdb_vector_index_t *v_index = xdb_load_vector_index_from_file("../../data/ip2region.xdb");
+    xdb_vector_index_t *v_index = xdb_load_vector_index_from_file("../../data/ip2region_v4.xdb");
     if (v_index == NULL) {
         printf("failed to load vector index from file\n");
     } else {
         printf("vector index loaded from file, length=%d\n", v_index->length);
     }
 
-    xdb_close_vector_index(v_index);
+    xdb_free_vector_index(v_index);
 }
 
 void test_load_content() {
-    xdb_content_t *content = xdb_load_content_from_file("../../data/ip2region.xdb");
+    xdb_content_t *content = xdb_load_content_from_file("../../data/ip2region_v4.xdb");
     if (content == NULL) {
         printf("failed to load content from file\n");
     } else {
         printf("content loaded from file, length=%d\n", content->length);
     }
 
-    xdb_close_content(content);
+    xdb_free_content(content);
 }
 
 // valgrind --tool=memcheck --leak-check=full ./a.out

binding/c/xdb_api.h

@@ -6,8 +6,8 @@
 // @Author Lion <chenxin619315@gmail.com>
 // @Date   2022/06/27
 
-#ifndef C_XDB_SEARCHER_H
+#ifndef C_IP2REGION_XDB_H
-#define C_XDB_SEARCHER_H
+#define C_IP2REGION_XDB_H
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -59,7 +59,7 @@ XDB_PUBLIC(xdb_header_t *) xdb_load_header(FILE *);
 
 XDB_PUBLIC(xdb_header_t *) xdb_load_header_from_file(const char *);
 
-XDB_PUBLIC(void) xdb_close_header(void *);
+XDB_PUBLIC(void) xdb_free_header(void *);
 
 
 // --- vector index buffer
@@ -73,7 +73,7 @@ XDB_PUBLIC(xdb_vector_index_t *) xdb_load_vector_index(FILE *);
 
 XDB_PUBLIC(xdb_vector_index_t *) xdb_load_vector_index_from_file(const char *);
 
-XDB_PUBLIC(void) xdb_close_vector_index(void *);
+XDB_PUBLIC(void) xdb_free_vector_index(void *);
 
 
 // --- content buffer
@@ -87,7 +87,7 @@ XDB_PUBLIC(xdb_content_t *) xdb_load_content(FILE *);
 
 XDB_PUBLIC(xdb_content_t *) xdb_load_content_from_file(const char *);
 
-XDB_PUBLIC(void) xdb_close_content(void *);
+XDB_PUBLIC(void) xdb_free_content(void *);
 
 // --- End buffer load
 
@@ -146,4 +146,4 @@ XDB_PUBLIC(unsigned int) xdb_mip(unsigned long, unsigned long);
 XDB_PUBLIC(long) xdb_now();
 
 
-#endif //C_XDB_SEARCHER_H
+#endif // C_IP2REGION_XDB_H

binding/c/xdb_searcher.c

@@ -6,35 +6,7 @@
 // @Author Lion <chenxin619315@gmail.com>
 // @Date   2022/06/27
 
-#include "xdb_searcher.h"
+#include "xdb_api.h"
-
-// for Linux
-#ifdef XDB_LINUX
-#include "sys/time.h"
-#endif
-
-// @Note: since 2023/10/13 to compatible with the windows system
-#ifdef XDB_WINDOWS
-#include <windows.h>
-XDB_PRIVATE(int) gettimeofday(struct timeval* tp, void* tzp) {
-    time_t clock;
-    struct tm tm;
-    SYSTEMTIME wtm;
-    GetLocalTime(&wtm);
-    tm.tm_year = wtm.wYear - 1900;
-    tm.tm_mon = wtm.wMonth - 1;
-    tm.tm_mday = wtm.wDay;
-    tm.tm_hour = wtm.wHour;
-    tm.tm_min = wtm.wMinute;
-    tm.tm_sec = wtm.wSecond;
-    tm.tm_isdst = -1;
-    clock = mktime(&tm);
-    tp->tv_sec = clock;
-    tp->tv_usec = wtm.wMilliseconds * 1000;
-    return (0);
-}
-#endif
-
 
 // internal function prototype define
 XDB_PRIVATE(int) read(xdb_searcher_t *, long offset, char *, size_t length);
@@ -196,234 +168,3 @@ XDB_PRIVATE(int) read(xdb_searcher_t *xdb, long offset, char *buffer, size_t len
 XDB_PUBLIC(int) xdb_get_io_count(xdb_searcher_t *xdb) {
     return xdb->io_count;
 }
-
-
-// --- buffer load util functions
-
-XDB_PUBLIC(xdb_header_t *) xdb_load_header(FILE *handle) {
-    xdb_header_t *header;
-    unsigned int size = xdb_header_info_length;
-
-    // entry alloc
-    header = (xdb_header_t *) xdb_malloc(sizeof(xdb_header_t));
-    if (header == NULL) {
-        return NULL;
-    }
-
-    if (fseek(handle, 0, SEEK_SET) == -1) {
-        xdb_free(header);
-        return NULL;
-    }
-
-    if (fread(header->buffer, 1,size, handle) != size) {
-        xdb_free(header);
-        return NULL;
-    }
-
-    // fill the fields
-    header->length = size;
-    header->version = (unsigned short) xdb_get_ushort(header->buffer, 0);
-    header->index_policy = (unsigned short) xdb_get_ushort(header->buffer, 2);
-    header->created_at = xdb_get_uint(header->buffer, 4);
-    header->start_index_ptr = xdb_get_uint(header->buffer, 8);
-    header->end_index_ptr = xdb_get_uint(header->buffer,12);
-
-    return header;
-}
-
-XDB_PUBLIC(xdb_header_t *) xdb_load_header_from_file(const char *db_path) {
-    xdb_header_t *header;
-    FILE *handle = fopen(db_path, "rb");
-    if (handle == NULL) {
-        return NULL;
-    }
-
-    header = xdb_load_header(handle);
-    fclose(handle);
-    return header;
-}
-
-XDB_PUBLIC(void) xdb_close_header(void *ptr) {
-    xdb_header_t *header = (xdb_header_t *) ptr;
-    if (header->length > 0) {
-        header->length = 0;
-        xdb_free(header);
-    }
-}
-
-// --- vector index
-
-XDB_PUBLIC(xdb_vector_index_t *) xdb_load_vector_index(FILE *handle) {
-    xdb_vector_index_t *v_index;
-    unsigned int size = xdb_vector_index_length;
-
-    // seek to the vector index offset
-    if (fseek(handle, xdb_header_info_length, SEEK_SET) == -1) {
-        return NULL;
-    }
-
-    // do the buffer read
-    v_index = (xdb_vector_index_t *) xdb_malloc(sizeof(xdb_vector_index_t));
-    if (v_index == NULL) {
-        return NULL;
-    }
-
-    v_index->length = size;
-    if (fread(v_index->buffer, 1, size, handle) != size) {
-        xdb_free(v_index);
-        return NULL;
-    }
-
-    return v_index;
-}
-
-XDB_PUBLIC(xdb_vector_index_t *) xdb_load_vector_index_from_file(const char *db_path) {
-    xdb_vector_index_t *v_index;
-    FILE *handle = fopen(db_path, "rb");
-    if (handle == NULL) {
-        return NULL;
-    }
-
-    v_index = xdb_load_vector_index(handle);
-    fclose(handle);
-    return v_index;
-}
-
-XDB_PUBLIC(void) xdb_close_vector_index(void *ptr) {
-    xdb_vector_index_t *v_index = (xdb_vector_index_t *) ptr;
-    if (v_index->length > 0) {
-        v_index->length = 0;
-        xdb_free(v_index);
-    }
-}
-
-// --- content buffer
-
-XDB_PUBLIC(xdb_content_t *) xdb_load_content(FILE *handle) {
-    unsigned int size;
-    xdb_content_t *content;
-
-    // determine the file size
-    if (fseek(handle, 0, SEEK_END) == -1) {
-        return NULL;
-    }
-
-    size = (unsigned int) ftell(handle);
-    if (fseek(handle, 0, SEEK_SET) == -1) {
-        return NULL;
-    }
-
-    // do the file read
-    content = (xdb_content_t *) xdb_malloc(sizeof(xdb_content_t));
-    if (content == NULL) {
-        return NULL;
-    }
-
-    // do the buffer alloc
-    content->buffer = (char *) xdb_malloc(size);
-    if (content->buffer == NULL) {
-        xdb_free(content);
-        return NULL;
-    }
-
-    // read the content into the buffer
-    content->length = size;
-    if (fread(content->buffer, 1, size, handle) != size) {
-        xdb_free(content);
-        return NULL;
-    }
-
-    return content;
-}
-
-XDB_PUBLIC(xdb_content_t *) xdb_load_content_from_file(const char *db_path) {
-    xdb_content_t *content;
-    FILE *handle = fopen(db_path, "rb");
-    if (handle == NULL) {
-        return NULL;
-    }
-
-    content = xdb_load_content(handle);
-    fclose(handle);
-    return content;
-}
-
-XDB_PUBLIC(void) xdb_close_content(void *ptr) {
-    xdb_content_t *content = (xdb_content_t *) ptr;
-    if (content->length > 0) {
-        content->length = 0;
-        xdb_free(content->buffer);
-        content->buffer = NULL;
-        xdb_free(content);
-    }
-}
-
-// --- End
-
-// get unsigned long (4bytes) from a specified buffer start from the specified offset
-XDB_PUBLIC(unsigned int) xdb_get_uint(const char *buffer, int offset) {
-    return (
-        ((buffer[offset  ]) & 0x000000FF) |
-        ((buffer[offset+1] <<  8) & 0x0000FF00) |
-        ((buffer[offset+2] << 16) & 0x00FF0000) |
-        ((buffer[offset+3] << 24) & 0xFF000000)
-    );
-}
-
-// get unsigned short (2bytes) from a specified buffer start from the specified offset
-XDB_PUBLIC(int) xdb_get_ushort(const char *buffer, int offset) {
-    return (
-        ((buffer[offset  ]) & 0x000000FF) |
-        ((buffer[offset+1] << 8) & 0x0000FF00)
-    );
-}
-
-// string ip to unsigned int
-static int shiftIndex[4] = {24, 16, 8, 0};
-XDB_PUBLIC(int) xdb_check_ip(const char *src_ip, unsigned int *dst_ip) {
-    char c;
-    int i, n, ip = 0;
-    const char *ptr = src_ip;
-    for (i = 0; i < 4; i++) {
-        n = 0;
-        while (1) {
-            c = *ptr;
-            ptr++;
-            if (c >= '0' && c <= '9') {
-                n *= 10;
-                n += c - '0';
-            } else if ((i < 3 && c == '.') || i == 3) {
-                // stopping at the '.' but ignore the tailing chars
-                // after the 3rd one (auto clean the tailing none-integer ?).
-                break;
-            } else {
-                return 1;
-            }
-        }
-
-        if (n > 0xFF) {
-            return 2;
-        }
-
-        ip |= (n << shiftIndex[i]);
-    }
-
-    *dst_ip = ip;
-    return 0;
-}
-
-// unsigned int ip to string ip
-XDB_PUBLIC(void) xdb_long2ip(unsigned int ip, char *buffer) {
-    sprintf(buffer, "%d.%d.%d.%d", (ip >> 24) & 0xFF, (ip >> 16) & 0xFF, (ip >> 8) & 0xFF, ip & 0xFF);
-}
-
-// get the middle ip of a and b
-XDB_PUBLIC(unsigned int) xdb_mip(unsigned long a, unsigned long b) {
-    return (unsigned int) ((a + b) >> 1);
-}
-
-XDB_PUBLIC(long) xdb_now() {
-    struct timeval c_time;
-    gettimeofday(&c_time, NULL);
-    return c_time.tv_sec * (int)1e6 + c_time.tv_usec;
-}

binding/c/xdb_util.c

@@ -0,0 +1,264 @@
+// Copyright 2022 The Ip2Region Authors. All rights reserved.
+// Use of this source code is governed by a Apache2.0-style
+// license that can be found in the LICENSE file.
+
+// ---
+// @Author Lion <chenxin619315@gmail.com>
+// @Date   2022/06/27
+
+#include "xdb_api.h"
+
+// for Linux
+#ifdef XDB_LINUX
+#include "sys/time.h"
+#endif
+
+// @Note: since 2023/10/13 to compatible with the windows system
+#ifdef XDB_WINDOWS
+#include <windows.h>
+XDB_PRIVATE(int) gettimeofday(struct timeval* tp, void* tzp) {
+    time_t clock;
+    struct tm tm;
+    SYSTEMTIME wtm;
+    GetLocalTime(&wtm);
+    tm.tm_year = wtm.wYear - 1900;
+    tm.tm_mon = wtm.wMonth - 1;
+    tm.tm_mday = wtm.wDay;
+    tm.tm_hour = wtm.wHour;
+    tm.tm_min = wtm.wMinute;
+    tm.tm_sec = wtm.wSecond;
+    tm.tm_isdst = -1;
+    clock = mktime(&tm);
+    tp->tv_sec = clock;
+    tp->tv_usec = wtm.wMilliseconds * 1000;
+    return (0);
+}
+#endif
+
+XDB_PUBLIC(xdb_header_t *) xdb_load_header(FILE *handle) {
+    xdb_header_t *header;
+    unsigned int size = xdb_header_info_length;
+
+    // entry alloc
+    header = (xdb_header_t *) xdb_malloc(sizeof(xdb_header_t));
+    if (header == NULL) {
+        return NULL;
+    }
+
+    if (fseek(handle, 0, SEEK_SET) == -1) {
+        xdb_free(header);
+        return NULL;
+    }
+
+    if (fread(header->buffer, 1,size, handle) != size) {
+        xdb_free(header);
+        return NULL;
+    }
+
+    // fill the fields
+    header->length = size;
+    header->version = (unsigned short) xdb_get_ushort(header->buffer, 0);
+    header->index_policy = (unsigned short) xdb_get_ushort(header->buffer, 2);
+    header->created_at = xdb_get_uint(header->buffer, 4);
+    header->start_index_ptr = xdb_get_uint(header->buffer, 8);
+    header->end_index_ptr = xdb_get_uint(header->buffer,12);
+
+    return header;
+}
+
+XDB_PUBLIC(xdb_header_t *) xdb_load_header_from_file(const char *db_path) {
+    xdb_header_t *header;
+    FILE *handle = fopen(db_path, "rb");
+    if (handle == NULL) {
+        return NULL;
+    }
+
+    header = xdb_load_header(handle);
+    fclose(handle);
+    return header;
+}
+
+XDB_PUBLIC(void) xdb_free_header(void *ptr) {
+    xdb_header_t *header = (xdb_header_t *) ptr;
+    if (header->length > 0) {
+        header->length = 0;
+        xdb_free(header);
+    }
+}
+
+// --- vector index
+
+XDB_PUBLIC(xdb_vector_index_t *) xdb_load_vector_index(FILE *handle) {
+    xdb_vector_index_t *v_index;
+    unsigned int size = xdb_vector_index_length;
+
+    // seek to the vector index offset
+    if (fseek(handle, xdb_header_info_length, SEEK_SET) == -1) {
+        return NULL;
+    }
+
+    // do the buffer read
+    v_index = (xdb_vector_index_t *) xdb_malloc(sizeof(xdb_vector_index_t));
+    if (v_index == NULL) {
+        return NULL;
+    }
+
+    v_index->length = size;
+    if (fread(v_index->buffer, 1, size, handle) != size) {
+        xdb_free(v_index);
+        return NULL;
+    }
+
+    return v_index;
+}
+
+XDB_PUBLIC(xdb_vector_index_t *) xdb_load_vector_index_from_file(const char *db_path) {
+    xdb_vector_index_t *v_index;
+    FILE *handle = fopen(db_path, "rb");
+    if (handle == NULL) {
+        return NULL;
+    }
+
+    v_index = xdb_load_vector_index(handle);
+    fclose(handle);
+    return v_index;
+}
+
+XDB_PUBLIC(void) xdb_free_vector_index(void *ptr) {
+    xdb_vector_index_t *v_index = (xdb_vector_index_t *) ptr;
+    if (v_index->length > 0) {
+        v_index->length = 0;
+        xdb_free(v_index);
+    }
+}
+
+// --- content buffer
+
+XDB_PUBLIC(xdb_content_t *) xdb_load_content(FILE *handle) {
+    unsigned int size;
+    xdb_content_t *content;
+
+    // determine the file size
+    if (fseek(handle, 0, SEEK_END) == -1) {
+        return NULL;
+    }
+
+    size = (unsigned int) ftell(handle);
+    if (fseek(handle, 0, SEEK_SET) == -1) {
+        return NULL;
+    }
+
+    // do the file read
+    content = (xdb_content_t *) xdb_malloc(sizeof(xdb_content_t));
+    if (content == NULL) {
+        return NULL;
+    }
+
+    // do the buffer alloc
+    content->buffer = (char *) xdb_malloc(size);
+    if (content->buffer == NULL) {
+        xdb_free(content);
+        return NULL;
+    }
+
+    // read the content into the buffer
+    content->length = size;
+    if (fread(content->buffer, 1, size, handle) != size) {
+        xdb_free(content);
+        return NULL;
+    }
+
+    return content;
+}
+
+XDB_PUBLIC(xdb_content_t *) xdb_load_content_from_file(const char *db_path) {
+    xdb_content_t *content;
+    FILE *handle = fopen(db_path, "rb");
+    if (handle == NULL) {
+        return NULL;
+    }
+
+    content = xdb_load_content(handle);
+    fclose(handle);
+    return content;
+}
+
+XDB_PUBLIC(void) xdb_free_content(void *ptr) {
+    xdb_content_t *content = (xdb_content_t *) ptr;
+    if (content->length > 0) {
+        content->length = 0;
+        xdb_free(content->buffer);
+        content->buffer = NULL;
+        xdb_free(content);
+    }
+}
+
+// --- End
+
+// get unsigned long (4bytes) from a specified buffer start from the specified offset
+XDB_PUBLIC(unsigned int) xdb_get_uint(const char *buffer, int offset) {
+    return (
+        ((buffer[offset  ]) & 0x000000FF) |
+        ((buffer[offset+1] <<  8) & 0x0000FF00) |
+        ((buffer[offset+2] << 16) & 0x00FF0000) |
+        ((buffer[offset+3] << 24) & 0xFF000000)
+    );
+}
+
+// get unsigned short (2bytes) from a specified buffer start from the specified offset
+XDB_PUBLIC(int) xdb_get_ushort(const char *buffer, int offset) {
+    return (
+        ((buffer[offset  ]) & 0x000000FF) |
+        ((buffer[offset+1] << 8) & 0x0000FF00)
+    );
+}
+
+// string ip to unsigned int
+static int shiftIndex[4] = {24, 16, 8, 0};
+XDB_PUBLIC(int) xdb_check_ip(const char *src_ip, unsigned int *dst_ip) {
+    char c;
+    int i, n, ip = 0;
+    const char *ptr = src_ip;
+    for (i = 0; i < 4; i++) {
+        n = 0;
+        while (1) {
+            c = *ptr;
+            ptr++;
+            if (c >= '0' && c <= '9') {
+                n *= 10;
+                n += c - '0';
+            } else if ((i < 3 && c == '.') || i == 3) {
+                // stopping at the '.' but ignore the tailing chars
+                // after the 3rd one (auto clean the tailing none-integer ?).
+                break;
+            } else {
+                return 1;
+            }
+        }
+
+        if (n > 0xFF) {
+            return 2;
+        }
+
+        ip |= (n << shiftIndex[i]);
+    }
+
+    *dst_ip = ip;
+    return 0;
+}
+
+// unsigned int ip to string ip
+XDB_PUBLIC(void) xdb_long2ip(unsigned int ip, char *buffer) {
+    sprintf(buffer, "%d.%d.%d.%d", (ip >> 24) & 0xFF, (ip >> 16) & 0xFF, (ip >> 8) & 0xFF, ip & 0xFF);
+}
+
+// get the middle ip of a and b
+XDB_PUBLIC(unsigned int) xdb_mip(unsigned long a, unsigned long b) {
+    return (unsigned int) ((a + b) >> 1);
+}
+
+XDB_PUBLIC(long) xdb_now() {
+    struct timeval c_time;
+    gettimeofday(&c_time, NULL);
+    return c_time.tv_sec * (int)1e6 + c_time.tv_usec;
+}