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2015
10-18

SVN 分支

分支操作创建另一条线路开发。它是有用的,当有人想开发过程叉成两个不同的方向。让我们假设发布的产品版本1.0中,可能要创建新的分支,所以可以保持独立,发展2.01.0 bug修复。

在本节中,我们将看到如何创建,遍历和合并分支。Jerry 已经沮丧,因为冲突,所以他决定创建新的私有分支。

[jerry@CentOS project_repo]$ ls
branches  tags  trunk

[jerry@CentOS project_repo]$ svn copy trunk branches/jerry_branch
A         branches/jerry_branch

[jerry@CentOS project_repo]$ svn status
A  +    branches/jerry_branch

[jerry@CentOS project_repo]$ svn commit -m "Jerry's private branch"
Adding         branches/jerry_branch
Adding         branches/jerry_branch/README

Committed revision 9.
[jerry@CentOS project_repo]$ 

Jerry 是在他的私人分支工作。他补充说数组的排序操作。Jerry 修改后的代码看起来是这样的。

[jerry@CentOS project_repo]$ cd branches/jerry_branch/

[jerry@CentOS jerry_branch]$ cat array.c 

上面的命令将产生以下结果

#include <stdio.h>

#define MAX 16

void bubble_sort(int *arr, int n)
{

   int i, j, temp, flag = 1;

   for (i = 1; i < n && flag == 1; ++i) {
      flag = 0;
      for (j = 0; j < n - i; ++j) {
         if (arr[j] > arr[j + 1]) {
            flag      	= 1;
            temp      	= arr[j];
            arr[j]      = arr[j + 1];
            arr[j + 1]	= temp;
         }
      }
   }
}

void accept_input(int *arr, int n)
{
   int i;

   for (i = 0; i < n; ++i)
      scanf("%d", &arr[i]);
}

void display(int *arr, int n)
{
   int i;

   for (i = 0; i < n; ++i)
      printf("|%d| ", arr[i]);

   printf("
");
}

int main(void)
{
   int i, n, key, ret, arr[MAX];

   printf("Enter the total number of elements: ");
   scanf("%d", &n);

   /* Error handling for array overflow */
   if (n >MAX) {
      fprintf(stderr, "Number of elements must be less than %d
", MAX);
      return 1;
   }

   printf("Enter the elements
");
   accept_input(arr, n);

   printf("Array has following elements
");
   display(arr, n);

   printf("Sorted data is
");
   bubble_sort(arr, n);
   display(arr, n);

   return 0;
}

Jerry 编译并测试自己的代码和准备提交他修改的变化。

[jerry@CentOS jerry_branch]$ make array
cc     array.c   -o array

[jerry@CentOS jerry_branch]$ ./array 

上面的命令将产生以下结果

Enter the total number of elements: 5
Enter the elements
10
-4
2
7 
9
Array has following elements
|10| |-4| |2| |7| |9| 
Sorted data is
|-4| |2| |7| |9| |10| 

[jerry@CentOS jerry_branch]$ svn status
?       array
M       array.c

[jerry@CentOS jerry_branch]$ svn commit -m "Added sort operation"
Sending        jerry_branch/array.c
Transmitting file data .
Committed revision 10.

同时通过躯干,Tom决定执行搜索操作。Tom搜索操作添加代码,他的代码看起来像这样。

[tom@CentOS trunk]$ svn diff

上面的命令将产生以下结果

Index: array.c
===================================================================
--- array.c   (revision 10)
+++ array.c   (working copy)
@@ -2,6 +2,27 @@
 
 #define MAX 16
 
+int bin_search(int *arr, int n, int key)
+{
+   int low, high, mid;
+
+   low   = 0;
+   high   = n - 1;
+   mid   = low + (high - low) / 2;
+
+   while (low <= high) {
+      if (arr[mid] == key)
+         return mid;
+      if (arr[mid] > key)
+         high = mid - 1;
+      else
+         low = mid + 1;
+      mid = low + (high - low) / 2;
+   }
+
+   return -1;
+}
+
 void accept_input(int *arr, int n)
 {
    int i;
@@ -22,7 +43,7 @@
 
 int main(void)
 {
-   int i, n, arr[MAX];
+   int i, n, ret, key, arr[MAX];
 
    printf("Enter the total number of elements: ");
    scanf("%d", &n);
@@ -39,5 +60,16 @@
    printf("Array has following elements
");
    display(arr, n);
 
+   printf("Enter the element to be searched: ");
+   scanf("%d", &key);
+
+   ret = bin_search(arr, n, key);
+   if (ret < 0) {
+      fprintf(stderr, "%d element not present in array
", key);
+      return 1;
+   }
+
+   printf("%d element found at location %d
", key, ret + 1);
+
    return 0;
 }

审查后,他提交了他修改的变化。

[tom@CentOS trunk]$ svn status
?       array
M       array.c

[tom@CentOS trunk]$ svn commit -m "Added search operation"
Sending        trunk/array.c
Transmitting file data .
Committed revision 11.

但Tom 好奇为什么 Jerry 一直在做他的私人分支。

[tom@CentOS trunk]$ cd ../branches/
[tom@CentOS branches]$ svn up
A    jerry_branch
A    jerry_branch/array.c
A    jerry_branch/README

[tom@CentOS branches]$ svn log
------------------------------------------------------------------------
r9 | jerry | 2013-08-27 21:56:51 +0530 (Tue, 27 Aug 2013) | 1 line

Added sort operation
------------------------------------------------------------------------

查看Subversion的日志消息,Tom发现,Jerry实现的排序操作。Tom执行搜索操作使用二进制搜索算法,它总是希望数据的排序顺序。但是,如果用户提供的数据,未排序的顺序呢?在这种情况下的二进制搜索操作将失败。于是,他决定采用Jerry 的代码,搜索操作前对数据进行排序。于是,他会要求Subversion的从Jerry的分支到主干合并代码。

[tom@CentOS trunk]$ pwd
/home/tom/project_repo/trunk

[tom@CentOS trunk]$ svn merge ../branches/jerry_branch/
--- Merging r9 through r11 into '.':
U    array.c

合并后array.c的这个样子。

[tom@CentOS trunk]$ cat array.c

上面的命令将产生以下结果

#include <stdio.h>

#define MAX 16

void bubble_sort(int *arr, int n)
{
   int i, j, temp, flag = 1;

   for (i = 1; i < n && flag == 1; ++i) {
      flag = 0;
      for (j = 0; j < n - i; ++j) {
         if (arr[j] > arr[j + 1]) {
            flag      	= 1;
            temp      	= arr[j];
            arr[j]      = arr[j + 1];
            arr[j + 1]	= temp;
         }
      }
   }
}

int bin_search(int *arr, int n, int key)
{
   int low, high, mid;

   low   = 0;
   high   = n - 1;
   mid   = low + (high - low) / 2;

   while (low <= high) {
      if (arr[mid] == key)
         return mid;
      if (arr[mid] > key)
         high = mid - 1;
      else
         low = mid + 1;
      mid = low + (high - low) / 2;
   }

   return -1;
}

void accept_input(int *arr, int n)
{
   int i;

   for (i = 0; i < n; ++i)
      scanf("%d", &arr[i]);
}

void display(int *arr, int n)
{
   int i;

   for (i = 0; i < n; ++i)
      printf("|%d| ", arr[i]);
   
   printf("
");
}

int main(void)
{
   int i, n, ret, key, arr[MAX];

   printf("Enter the total number of elements: ");
   scanf("%d", &n);

   /* Error handling for array overflow */
   if (n > MAX) {
      fprintf(stderr, "Number of elements must be less than %d
", MAX);
      return 1;
   }

   printf("Enter the elements
");
   accept_input(arr, n);

   printf("Array has following elements
");
   display(arr, n);

   printf("Sorted data is
");
   bubble_sort(arr, n);
   display(arr, n);

   printf("Enter the element to be searched: ");
   scanf("%d", &key);

   ret = bin_search(arr, n, key);
   if (ret < 0) {
      fprintf(stderr, "%d element not present in array
", key);
      return 1;
   }

   printf("%d element found at location %d
", key, ret + 1);

   return 0;
}

Tom 测试完成后,提交他的修改到版本库。

[tom@CentOS trunk]$ make array
cc     array.c   -o array

[tom@CentOS trunk]$ ./array 
Enter the total number of elements: 5
Enter the elements
10
-2
8
15
3
Array has following elements
|10| |-2| |8| |15| |3| 
Sorted data is
|-2| |3| |8| |10| |15| 
Enter the element to be searched: -2
-2 element found at location 1

[tom@CentOS trunk]$ svn commit -m "Merge changes from Jerry's code"
Sending        trunk
Sending        trunk/array.c
Transmitting file data .
Committed revision 12.

[tom@CentOS trunk]$ 

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