diff --git a/binding/c/main.c b/binding/c/main.c
index e252f48..309ba85 100644
--- a/binding/c/main.c
+++ b/binding/c/main.c
@@ -7,9 +7,74 @@
 // @Date   2022/06/28
 
 #include "stdio.h"
-#include "sys/time.h"
 #include "xdb_searcher.h"
 
+struct searcher_test_entry {
+    xdb_searcher_t searcher;
+    char *v_index;
+    char *c_buffer;
+};
+typedef struct searcher_test_entry searcher_test_t;
+
+int init_searcher_test(searcher_test_t *test, char *db_path, char *cache_policy) {
+    int err;
+    test->v_index = NULL;
+    test->c_buffer = NULL;
+
+    if (strcmp(cache_policy, "file") == 0) {
+        err = xdb_new_with_file_only(&test->searcher, db_path);
+        if (err != 0) {
+            printf("failed to create searcher with errcode=%d\n", err);
+            return 1;
+        }
+    } else if (strcmp(cache_policy, "vectorIndex") == 0) {
+        test->v_index = xdb_load_vector_index_from_file(db_path);
+        if (test->v_index == NULL) {
+            printf("failed to load vector index from `%s`\n", db_path);
+            return 2;
+        }
+
+        err = xdb_new_with_vector_index(&test->searcher, db_path, test->v_index);
+        if (err != 0) {
+            printf("failed to create vector index cached searcher with errcode=%d\n", err);
+            return 3;
+        }
+    } else if (strcmp(cache_policy, "content") == 0) {
+        test->c_buffer = xdb_load_content_from_file(db_path);
+        if (test->c_buffer == NULL) {
+            printf("failed to load xdb content from `%s`\n", db_path);
+            return 4;
+        }
+
+        err = xdb_new_with_buffer(&test->searcher, test->c_buffer);
+        if (err != 0) {
+            printf("failed to create content cached searcher with errcode=%d\n", err);
+            return 5;
+        }
+    } else {
+        printf("invalid cache policy `%s`, options: file/vectorIndex/content\n", cache_policy);
+        return 6;
+    }
+
+    return 0;
+}
+
+void destroy_searcher_test(searcher_test_t *test) {
+    xdb_close(&test->searcher);
+
+    // check and free the vector index
+    if (test->v_index != NULL) {
+        xdb_free(test->v_index);
+        test->v_index = NULL;
+    }
+
+    // check and free the content buffer
+    if (test->c_buffer != NULL) {
+        xdb_free(test->c_buffer);
+        test->c_buffer = NULL;
+    }
+}
+
 //read a line from a command line.
 static char *get_line(FILE *fp, char *__dst) {
     register int c;
@@ -43,7 +108,8 @@ void test_search(int argc, char *argv[]) {
     // for search
     long s_time, c_time;
     unsigned int ip;
-    char line[256] = {'\0'}, region[256] = {'\0'};
+    char line[512] = {'\0'}, region[512] = {'\0'};
+    searcher_test_t test;
 
     for (i = 2; i < argc; i++) {
         r = argv[i];
@@ -87,41 +153,9 @@ void test_search(int argc, char *argv[]) {
     }
 
     // printf("db_file=%s, cache_policy=%s\n", db_file, cache_policy);
-
-    xdb_searcher_t searcher;
-    char *vIndex = NULL, *cBuffer = NULL;
-    if (strcmp(cache_policy, "file") == 0) {
-        err = xdb_new_with_file_only(&searcher, db_file);
-        if (err != 0) {
-            printf("failed to create searcher with errcode=%d\n", err);
-            return;
-        }
-    } else if (strcmp(cache_policy, "vectorIndex") == 0) {
-        vIndex = xdb_load_vector_index_from_file(db_file);
-        if (vIndex == NULL) {
-            printf("failed to load vector index from `%s`\n", db_file);
-            return;
-        }
-
-        err = xdb_new_with_vector_index(&searcher, db_file, vIndex);
-        if (err != 0) {
-            printf("failed to create vector index cached searcher with errcode=%d\n", err);
-            return;
-        }
-    } else if (strcmp(cache_policy, "content") == 0) {
-        cBuffer = xdb_load_content_from_file(db_file);
-        if (cBuffer == NULL) {
-            printf("failed to load xdb content from `%s`\n", db_file);
-            return;
-        }
-
-        err = xdb_new_with_buffer(&searcher, cBuffer);
-        if (err != 0) {
-            printf("failed to create content cached searcher with errcode=%d\n", err);
-            return;
-        }
-    } else {
-        printf("invalid cache policy `%s`, options: file/vectorIndex/content\n", cache_policy);
+    err = init_searcher_test(&test, db_file, cache_policy);
+    if (err != 0) {
+        // init program will print the error reasons;
         return;
     }
 
@@ -138,35 +172,38 @@ void test_search(int argc, char *argv[]) {
             break;
         }
 
-        if (check_ip(line, &ip) != 0) {
+        if (xdb_check_ip(line, &ip) != 0) {
             printf("invalid ip address `%s`\n", line);
             continue;
         }
 
         s_time = xdb_now();
-        err = xdb_search(&searcher, ip, region, sizeof(region));
+        err = xdb_search(&test.searcher, ip, region, sizeof(region));
         if (err != 0) {
-            printf("{err: %d, io_count: %d}\n", err, xdb_get_io_count(&searcher));
+            printf("{err: %d, io_count: %d}\n", err, xdb_get_io_count(&test.searcher));
         } else {
             c_time = xdb_now() - s_time;
-            printf("{region: %s, io_count: %d, took: %ld μs}\n", region, xdb_get_io_count(&searcher), c_time);
+            printf("{region: %s, io_count: %d, took: %ld μs}\n", region, xdb_get_io_count(&test.searcher), c_time);
         }
     }
 
-    xdb_close(&searcher);
-    if (vIndex != NULL) {
-        xdb_free(vIndex);
-    }
-    if(cBuffer != NULL) {
-        xdb_free(cBuffer);
-    }
+    destroy_searcher_test(&test);
     printf("searcher test program exited, thanks for trying\n");
 }
 
 void test_bench(int argc, char *argv[]) {
-    int i, n;
+    int i, n, err;
     char *r, key[33] = {'\0'}, val[256] = {'\0'};
     char db_file[256] = {'\0'}, src_file[256] = {'\0'}, cache_policy[16] = {"vectorIndex"};
+
+    FILE *handle;
+    char line[1024] = {'\0'}, sip_str[16] = {'\0'}, eip_str[16] = {'\0'};
+    char src_region[512] = {'\0'}, region_buffer[512] = {'\0'};
+    unsigned int sip, eip, mip, ip_list[5];
+    int count = 0, took;
+    long s_time, t_time, c_time = 0;
+    searcher_test_t test;
+
     for (i = 2; i < argc; i++) {
         r = argv[i];
         if (strlen(r) < 5) {
@@ -209,7 +246,76 @@ void test_bench(int argc, char *argv[]) {
         return;
     }
 
-    printf("db_file=%s, src_file=%s, cache_policy=%s\n", db_file, src_file, cache_policy);
+    // printf("db_file=%s, src_file=%s, cache_policy=%s\n", db_file, src_file, cache_policy);
+    s_time = xdb_now();
+    err = init_searcher_test(&test, db_file, cache_policy);
+    if (err != 0) {
+        // the init function will print the details;
+        return;
+    }
+
+    // open the source file
+    handle = fopen(src_file, "r");
+    if (handle == NULL) {
+        printf("failed to open source text file `%s`\n", src_file);
+        return;
+    }
+
+    while(fgets(line, sizeof(line), handle) != NULL) {
+        n = sscanf(line, "%15[^|]|%15[^|]|%511[^\n]", sip_str, eip_str, src_region);
+        if (n != 3) {
+            printf("invalid ip segment line `%s`\n", line);
+            return;
+        }
+
+        if (xdb_check_ip(sip_str, &sip) != 0) {
+            printf("invalid start ip `%s`\n", sip_str);
+            return;
+        }
+
+        if (xdb_check_ip(eip_str, &eip) != 0) {
+            printf("invalid end ip `%s`\n", sip_str);
+            return;
+        }
+
+        if (sip > eip) {
+            printf("start ip(%s) should not be greater than end ip(%s)\n", sip_str, eip_str);
+            return;
+        }
+
+        mip = xdb_mip(sip, eip);
+        ip_list[0] = sip;
+        ip_list[1] = xdb_mip(sip, mip);
+        ip_list[2] = mip;
+        ip_list[3] = xdb_mip(mip, eip);
+        ip_list[4] = eip;
+        for (i = 0; i < 5; i++) {
+            t_time = xdb_now();
+            err = xdb_search(&test.searcher, ip_list[i], region_buffer, sizeof(region_buffer));
+            if (err != 0) {
+                xdb_long2ip(ip_list[i], sip_str);
+                printf("failed to search ip `%s` with errno=%d\n", sip_str, err);
+                return;
+            }
+
+            c_time += xdb_now() - t_time;
+
+            // check the region info
+            if (strcmp(region_buffer, src_region) != 0) {
+                xdb_long2ip(ip_list[i], sip_str);
+                printf("failed to search(%s) with (%s != %s)\n", sip_str, region_buffer, src_region);
+                return;
+            }
+
+            count++;
+        }
+    };
+
+    took = xdb_now() - s_time;
+    destroy_searcher_test(&test);
+    fclose(handle);
+    printf("Bench finished, {cache_policy: %s, total: %d, took: %.3fs, cost: %d μs/op}\n",
+           cache_policy, count, took/1e6, count == 0 ? 0 : (int)(c_time/count));
 }
 
 int main(int argc, char *argv[]) {
diff --git a/binding/c/util_test.c b/binding/c/util_test.c
index 1d51750..3a35230 100644
--- a/binding/c/util_test.c
+++ b/binding/c/util_test.c
@@ -20,13 +20,13 @@ void test_check_ip() {
     unsigned int ip;
     char ip_buff[16] = {'\0'};
     for (i = 0; i < 11; i++) {
-        errcode = check_ip(ip_list[i], &ip);
+        errcode = xdb_check_ip(ip_list[i], &ip);
         if (errcode != 0) {
             printf("invalid ip address `%s`\n", ip_list[i]);
             continue;
         }
 
-        long2ip(ip, ip_buff);
+        xdb_long2ip(ip, ip_buff);
         printf("long(%-15s)=%-10u, long2ip(%-10u)=%-15s", ip_list[i], ip, ip, ip_buff);
         if (strcmp(ip_list[i], ip_buff) != 0) {
             printf(" --[Failed]\n");
diff --git a/binding/c/xdb_searcher.c b/binding/c/xdb_searcher.c
index 7ec46a9..452aadd 100644
--- a/binding/c/xdb_searcher.c
+++ b/binding/c/xdb_searcher.c
@@ -57,7 +57,7 @@ XDB_PUBLIC(void) xdb_close(xdb_searcher_t *xdb) {
 
 XDB_PUBLIC(int) xdb_search_by_string(xdb_searcher_t *xdb, const char *str_ip, char *region_buffer, size_t length) {
     unsigned int ip = 0;
-    int errcode = check_ip(str_ip, &ip);
+    int errcode = xdb_check_ip(str_ip, &ip);
     if (errcode != 0) {
         return 10 + errcode;
     } else {
@@ -78,19 +78,19 @@ XDB_PUBLIC(int) xdb_search(xdb_searcher_t *xdb, unsigned int ip, char *region_bu
     il1 = ((int) (ip >> 16)) & 0xFF;
     idx = il0 * xdb_vector_index_cols * xdb_vector_index_size + il1 * xdb_vector_index_size;
     if (xdb->vector_index != NULL) {
-        s_ptr = get_unsigned_int(xdb->vector_index, idx);
-        e_ptr = get_unsigned_int(xdb->vector_index, idx + 4);
+        s_ptr = xdb_get_uint(xdb->vector_index, idx);
+        e_ptr = xdb_get_uint(xdb->vector_index, idx + 4);
     } else if (xdb->content_buff != NULL) {
-        s_ptr = get_unsigned_int(xdb->content_buff, xdb_header_info_length + idx);
-        e_ptr = get_unsigned_int(xdb->content_buff, xdb_header_info_length + idx + 4);
+        s_ptr = xdb_get_uint(xdb->content_buff, xdb_header_info_length + idx);
+        e_ptr = xdb_get_uint(xdb->content_buff, xdb_header_info_length + idx + 4);
     } else {
         err = read(xdb, xdb_header_info_length + idx, vector_buffer, sizeof(vector_buffer));
         if (err != 0) {
             return 10 + err;
         }
 
-        s_ptr = get_unsigned_int(vector_buffer, 0);
-        e_ptr = get_unsigned_int(vector_buffer, 4);
+        s_ptr = xdb_get_uint(vector_buffer, 0);
+        e_ptr = xdb_get_uint(vector_buffer, 4);
     }
 
     // printf("s_ptr=%u, e_ptr=%u\n", s_ptr, e_ptr);
@@ -108,16 +108,16 @@ XDB_PUBLIC(int) xdb_search(xdb_searcher_t *xdb, unsigned int ip, char *region_bu
         }
 
         // decode the data fields as needed
-        sip = get_unsigned_int(segment_buffer, 0);
+        sip = xdb_get_uint(segment_buffer, 0);
         if (ip < sip) {
             h = m - 1;
         } else {
-            eip = get_unsigned_int(segment_buffer, 4);
+            eip = xdb_get_uint(segment_buffer, 4);
             if (ip > eip) {
                 l = m + 1;
             } else {
-                data_len = get_unsigned_short(segment_buffer, 8);
-                data_ptr = get_unsigned_int(segment_buffer, 10);
+                data_len = xdb_get_ushort(segment_buffer, 8);
+                data_ptr = xdb_get_uint(segment_buffer, 10);
                 break;
             }
         }
@@ -183,11 +183,11 @@ XDB_PUBLIC(int) xdb_load_header(FILE *handle, xdb_header_t *header) {
     }
 
     // fill the fields
-    header->version = (unsigned short) get_unsigned_short(buffer, 0);
-    header->index_policy = (unsigned short) get_unsigned_short(buffer, 2);
-    header->created_at = get_unsigned_int(buffer, 4);
-    header->start_index_ptr = get_unsigned_int(buffer, 8);
-    header->end_index_ptr = get_unsigned_int(buffer,12);
+    header->version = (unsigned short) xdb_get_ushort(buffer, 0);
+    header->index_policy = (unsigned short) xdb_get_ushort(buffer, 2);
+    header->created_at = xdb_get_uint(buffer, 4);
+    header->start_index_ptr = xdb_get_uint(buffer, 8);
+    header->end_index_ptr = xdb_get_uint(buffer,12);
 
     return 0;
 }
@@ -274,7 +274,7 @@ XDB_PUBLIC(char *) xdb_load_content_from_file(char *db_path) {
 // --- End
 
 // get unsigned long (4bytes) from a specified buffer start from the specified offset
-XDB_PUBLIC(unsigned int) get_unsigned_int(const char *buffer, int offset) {
+XDB_PUBLIC(unsigned int) xdb_get_uint(const char *buffer, int offset) {
     return (
         ((buffer[offset  ]) & 0x000000FF) |
         ((buffer[offset+1] <<  8) & 0x0000FF00) |
@@ -284,7 +284,7 @@ XDB_PUBLIC(unsigned int) get_unsigned_int(const char *buffer, int offset) {
 }
 
 // get unsigned short (2bytes) from a specified buffer start from the specified offset
-XDB_PUBLIC(int) get_unsigned_short(const char *buffer, int offset) {
+XDB_PUBLIC(int) xdb_get_ushort(const char *buffer, int offset) {
     return (
         ((buffer[offset  ]) & 0x000000FF) |
         ((buffer[offset+1] << 8) & 0x0000FF00)
@@ -293,7 +293,7 @@ XDB_PUBLIC(int) get_unsigned_short(const char *buffer, int offset) {
 
 // string ip to unsigned int
 static int shiftIndex[4] = {24, 16, 8, 0};
-XDB_PUBLIC(int) check_ip(const char *src_ip, unsigned int *dst_ip) {
+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;
@@ -326,10 +326,15 @@ XDB_PUBLIC(int) check_ip(const char *src_ip, unsigned int *dst_ip) {
 }
 
 // unsigned int ip to string ip
-XDB_PUBLIC(void) long2ip(unsigned int ip, char *buffer) {
+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);
diff --git a/binding/c/xdb_searcher.h b/binding/c/xdb_searcher.h
index 665f5d9..13b7725 100644
--- a/binding/c/xdb_searcher.h
+++ b/binding/c/xdb_searcher.h
@@ -101,16 +101,19 @@ XDB_PUBLIC(char *) xdb_load_content_from_file(char *);
 
 
 // get unsigned long (4bytes) from a specified buffer start from the specified offset with little-endian
-XDB_PUBLIC(unsigned int) get_unsigned_int(const char *, int);
+XDB_PUBLIC(unsigned int) xdb_get_uint(const char *, int);
 
 // get unsigned short (2bytes) from a specified buffer start from the specified offset with little-endian
-XDB_PUBLIC(int) get_unsigned_short(const char *, int);
+XDB_PUBLIC(int) xdb_get_ushort(const char *, int);
 
 // check the specified string ip and convert it to an unsigned int
-XDB_PUBLIC(int) check_ip(const char *, unsigned int *);
+XDB_PUBLIC(int) xdb_check_ip(const char *, unsigned int *);
 
 // unsigned int ip to string ip
-XDB_PUBLIC(void) long2ip(unsigned int, char *);
+XDB_PUBLIC(void) xdb_long2ip(unsigned int, char *);
+
+// get the middle ip of a and b
+XDB_PUBLIC(unsigned int) xdb_mip(unsigned long, unsigned long);
 
 // get the current time in microseconds
 XDB_PUBLIC(long) xdb_now();