SVN分支


分支操作建立另一條線路開發。它是有用的,當有人想開發過程叉成兩個不同的方向。讓我們假設發布的產品版本1.0中,可能要建立新的分支,所以可以保持獨立,發展2.01.0 bug修復。

在本節中,我們將看到如何建立,遍歷和合併分支。Jerry 已經沮喪,因為衝突,所以他決定建立新的私有分支。

[[email protected] project_repo]$ ls
branches  tags  trunk

[[email protected] project_repo]$ svn copy trunk branches/jerry_branch
A         branches/jerry_branch

[[email protected] project_repo]$ svn status
A  +    branches/jerry_branch

[[email protected] project_repo]$ svn commit -m "Jerry's private branch"
Adding         branches/jerry_branch
Adding         branches/jerry_branch/README

Committed revision 9.
[[email protected] project_repo]$ 

Jerry 是在他的私人分支工作。他補充說陣列的排序操作。Jerry 修改後的程式碼看起來是這樣的。

[[email protected] project_repo]$ cd branches/jerry_branch/

[[email protected] jerry_branch]$ cat array.c 

上面的命令將產生以下結果

#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 編譯並測試自己的程式碼和準備提交他修改的變化。

[[email protected] jerry_branch]$ make array
cc     array.c   -o array

[[email protected] jerry_branch]$ ./array 

上面的命令將產生以下結果

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| 

[[email protected] jerry_branch]$ svn status
?       array
M       array.c

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

同時通過軀幹,Tom決定執行搜尋操作。Tom搜尋操作新增程式碼,他的程式碼看起來像這樣。

[[email protected] trunk]$ svn diff

上面的命令將產生以下結果

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;
 }

審查後,他提交了他修改的變化。

[[email protected] trunk]$ svn status
?       array
M       array.c

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

但Tom 好奇為什麼 Jerry 一直在做他的私人分支。

[[email protected] trunk]$ cd ../branches/
[[email protected] branches]$ svn up
A    jerry_branch
A    jerry_branch/array.c
A    jerry_branch/README

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

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

檢視Subversion的紀錄檔訊息,Tom發現,Jerry實現的排序操作。Tom執行搜尋操作使用二進位制搜尋演算法,它總是希望資料的排序順序。但是,如果使用者提供的資料,未排序的順序呢?在這種情況下的二進位制搜尋操作將失敗。於是,他決定採用Jerry 的程式碼,搜尋操作前對資料進行排序。於是,他會要求Subversion的從Jerry的分支到主幹合併程式碼。

[[email protected] trunk]$ pwd
/home/tom/project_repo/trunk

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

合併後array.c的這個樣子。

[[email protected] trunk]$ cat array.c

上面的命令將產生以下結果

#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 測試完成後,提交他的修改到版本庫。

[[email protected] trunk]$ make array
cc     array.c   -o array

[[email protected] 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

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

[[email protected] trunk]$