PHP企業級應用之常見緩存技術篇
摘要：本文主要講解PHP企業級應用之常見緩存技術，從基本的PHP緩存概念到技術代碼的實現都深入做了解讀。數據緩存：這里所說的數據緩存是指數據庫查詢緩存。
普遍緩存技術
數據緩存：這里所說的數據緩存是指數據庫查詢緩存，每次訪問頁面的時候,都會先檢測相應的緩存數據是否存在，如果不存在，就連接數據庫，得到數據， 并把查詢結果序列化后保存到文件中，以后同樣的查詢結果就直接從緩存表或文件中獲得。
用的最廣的例子看Discuz的搜索功能，把結果ID緩存到一個表中，下次搜索相同關鍵字時先搜索緩存表。
舉個常用的方法，多表關聯的時候，把附表中的內容生成數組保存到主表的一個字段中，需要的時候數組分解一下，這樣的好處是只讀一個表，壞處就是兩個 數據同步會多不少步驟，數據庫永遠是瓶頸，用硬盤換速度，是這個的關鍵點。
頁面緩存：
每次訪問頁面的時候，都會先檢測相應的緩存頁面文件是否存在，如果不存在，就連接數據庫，得到數據，顯示頁面并同時生成緩存頁面文件，這樣下次訪問 的時候頁面文件就發揮作用了。(模板引擎和網上常見的一些緩存類通常有此功能)
時間觸發緩存：
檢查文件是否存在并且時間戳小于設置的過期時間,如果文件修改的時間戳比當前時間戳減去過期時間戳大，那么就用緩存，否則更新緩存。
內容觸發緩存：
當插入數據或更新數據時，強制更新緩存。
靜態緩存：
這里所說的靜態緩存是指靜態化，直接生成HTML或xml等文本文件，有更新的時候重生成一次，適合于不太變化的頁面，這就不說了。
以上內容是代碼級的解決方案，我直接CP別的框架，也懶得改，內容都差不多，很容易就做到，而且會幾種方式一起用，但下面的內容是服務器端的緩存方 案，非代碼級的，要有多方的合作才能做到
內存緩存:
Memcached是高性能的，分布式的內存對象緩存系統，用于在動態應用中減少數據庫負載，提升訪問速度。
這里說下Memcached的例子：
1. <?php
2. $memcache = new Memcache;
3. $memcache->connect(‘localhost’, 11211) or die (“Could not connect”);
4. $version = $memcache->getVersion();
5. echo “Server’s version: “.$version.”\n”;
6. $tmp_object = new stdClass;
7. $tmp_object->str_attr = ‘test’;
8. $tmp_object->int_attr = 123;
9. $memcache->set(‘key’, $tmp_object, false, 10) or die (“Failed to save data at the server”);
10. echo “Store data in the cache (data will expire in 10 seconds)\n”;
11. $get_result = $memcache->get(‘key’);
12. echo “Data from the cache:\n”;
13. var_dump($get_result);
14. ?>
2. $memcache = new Memcache;
3. $memcache->connect(‘localhost’, 11211) or die (“Could not connect”);
4. $version = $memcache->getVersion();
5. echo “Server’s version: “.$version.”\n”;
6. $tmp_object = new stdClass;
7. $tmp_object->str_attr = ‘test’;
8. $tmp_object->int_attr = 123;
9. $memcache->set(‘key’, $tmp_object, false, 10) or die (“Failed to save data at the server”);
10. echo “Store data in the cache (data will expire in 10 seconds)\n”;
11. $get_result = $memcache->get(‘key’);
12. echo “Data from the cache:\n”;
13. var_dump($get_result);
14. ?>
讀庫的例子：
1. <?php
2. $sql = ‘SELECT * FROM users’;
3. $key = md5($sql); //memcached 對象標識符
4. if ( !($datas = $mc->get($key)) ) {
5. // 在 memcached 中未獲取到緩存數據，則使用數據庫查詢獲取記錄集。
6. echo “n”.str_pad(‘Read datas from MySQL.’, 60, ‘_’).”n”;
7. $conn = mysql_connect(‘localhost’, ‘test’, ‘test’);
8. mysql_select_db(‘test’);
9. $result = mysql_query($sql);
10. while ($row = mysql_fetch_object($result))
11. $datas[] = $row;
12. // 將數據庫中獲取到的結果集數據保存到 memcached 中，以供下次訪問時使用。
13. $mc->add($key, $datas);
14. } else {
15. echo “n”.str_pad(‘Read datas from memcached.’, 60, ‘_’).”n”;
16. }
17. var_dump($datas);
18. ?>
2. $sql = ‘SELECT * FROM users’;
3. $key = md5($sql); //memcached 對象標識符
4. if ( !($datas = $mc->get($key)) ) {
5. // 在 memcached 中未獲取到緩存數據，則使用數據庫查詢獲取記錄集。
6. echo “n”.str_pad(‘Read datas from MySQL.’, 60, ‘_’).”n”;
7. $conn = mysql_connect(‘localhost’, ‘test’, ‘test’);
8. mysql_select_db(‘test’);
9. $result = mysql_query($sql);
10. while ($row = mysql_fetch_object($result))
11. $datas[] = $row;
12. // 將數據庫中獲取到的結果集數據保存到 memcached 中，以供下次訪問時使用。
13. $mc->add($key, $datas);
14. } else {
15. echo “n”.str_pad(‘Read datas from memcached.’, 60, ‘_’).”n”;
16. }
17. var_dump($datas);
18. ?>
PHP的緩沖器：
有eaccelerator， apc， PHPa，xcache，這個這個就不說了吧，搜索一堆一堆的，自己看啦，知道有這玩意就OK
MYSQL緩存：
這也算非代碼級的，經典的數據庫就是用的這種方式，看下面的運行時間，0.09xxx之類的。
我貼段根據藍色那家伙修改后部分my.ini 吧，2G的MYISAM表可以在0.05S左右，據說他前后改了有快一年
1. [client]
2. ……
3. default-character-set=gbk
4. default-storage-engine=MYISAM
5. max_connections=600
6. max_connect_errors=500
7. back_log=200
8. interactive_timeout=7200
9. query_cache_size=64M
10. ……
11. table_cache=512
12. ……
13. myisam_max_sort_file_size=100G
14. myisam_max_extra_sort_file_size=100G
15. myisam_sort_buffer_size=128M
16. key_buffer_size=1024M
17. read_buffer_size=512M
18. ……
19. thread_concurrency=8
2. ……
3. default-character-set=gbk
4. default-storage-engine=MYISAM
5. max_connections=600
6. max_connect_errors=500
7. back_log=200
8. interactive_timeout=7200
9. query_cache_size=64M
10. ……
11. table_cache=512
12. ……
13. myisam_max_sort_file_size=100G
14. myisam_max_extra_sort_file_size=100G
15. myisam_sort_buffer_size=128M
16. key_buffer_size=1024M
17. read_buffer_size=512M
18. ……
19. thread_concurrency=8
基于反向代理的Web緩存:
如Nginx，SQUID，mod_PRoxy(apache2以上又分為mod_proxy和mod_cache)
NGINX的例子
1. <nginx.conf>
2. #user nobody;
3. worker_processes 4;
4. error_log logs/error.log crit;
5. pid logs/nginx.pid;
6. worker_rlimit_nofile 10240;
7. events {
8. use epoll;
9. worker_connections 51200;
10. }
11. http {
12. include mime.types;
13. default_type application/octet-stream;
14. sendfile on;
15. keepalive_timeout 65;
16. tcp_nodelay on;
17. # server pool
18. upstream bspfrontsvr {
19. server 10.10.10.224:80 weight=1;
20. server 10.10.10.221:80 weight=1;
21. }
22.
23. upstream bspimgsvr {
24. server 10.10.10.201:80 weight=1;
25. }
26.
27. upstream bspstylesvr {
28. server 10.10.10.202:80 weight=1;
29. }
30.
31. upstream bsphelpsvr {
32. server 10.10.10.204:80 weight=1;
33. }
34.
35. upstream bspwsisvr {
36. server 10.10.10.203:80 weight=1;
37. }
38.
39. upstream bspadminsvr {
40. server 10.10.10.222:80 weight=1;
41. }
42.
43. upstream bspbuyersvr {
44. server 10.10.10.223:80 weight=1;
45. }
46.
47. upstream bspsellersvr {
48. server 10.10.10.225:80 weight=1;
49. }
50. upstream bsploginsvr {
51. server 10.10.10.220:443 weight=1;
52. }
53. upstream bspregistersvr {
54. server 10.10.10.220:80 weight=1;
55. }
56. log_format test_com ‘$remote_addr – $remote_user [$time_local] “$request” ‘
57. ‘$status $body_bytes_sent “$http_referer” “$http_user_agent” ‘;
58. #——————————————————————–
59. #img.test.com
60. server {
61. listen 10.10.10.230:80;
62. server_name img.test.com;
63. location / {
64. proxy_pass http://bspimgsvr;
65. include proxy_setting.conf;
66. }
67. access_log logs/img.log test_com;
68. }
69.
70. #style.test.com
71. server {
72. listen 10.10.10.230:80;
73. server_name style.test.com;
74. location / {
75. proxy_pass http://bspstylesvr;
76. include proxy_setting.conf;
77. }
78. access_log logs/style.log test_com;
79. }
80.
81. #help.test.com
82. server {
83. listen 10.10.10.230:80;
84. server_name help.test.com;
85. location / {
86. proxy_pass http://bsphelpsvr;
87. include proxy_setting.conf;
88. }
89. access_log logs/help.log test_com;
90. }
91.
92. #admin.test.com
93. server {
94. listen 10.10.10.230:80;
95. server_name admin.test.com;
96. location / {
97. proxy_pass http://bspadminsvr;
98. include proxy_setting.conf;
99. }
100. access_log logs/admin.log test_com;
101. }
102.
103. #buyer.test.com
104. server {
105. listen 10.10.10.230:80;
106. server_name buyer.test.com;
107. location / {
108. proxy_pass http://bspbuyersvr;
109. include proxy_setting.conf;
110. }
111. access_log logs/buyer.log test_com;
112. }
113.
114. #seller.test.com
115. server {
116. listen 10.10.10.230:80;
117. server_name seller.test.com;
118. location / {
119. proxy_pass http://bspsellersvr;
120. include proxy_setting.conf;
121. }
122. access_log logs/seller.log test_com;
123. }
124. #wsi.test.com
125. server {
126. listen 10.10.10.230:80;
127. server_name wsi.test.com;
128. location / {
129. proxy_pass http://bspwsisvr;
130. include proxy_setting.conf;
131. }
132. access_log logs/wsi.log test_com;
133. }
134. #www.test.com
135. server {
136. listen 10.10.10.230:80;
137. server_name www.test.com *.test.com;
138. location ~ ^/NginxStatus/ {
139. stub_status on;
140. access_log off;
141. }
142. location / {
143. proxy_pass http://bspfrontsvr;
144. include proxy_setting.conf;
145. }
146. access_log logs/www.log test_com;
147. error_page 500 502 503 504 /50x.html;
148. location = /50x.html {
149. root html;
150. }
151. }
152. #login.test.com
153. server {
154. listen 10.10.10.230:443;
155. server_name login.test.com;
156. ssl on;
157. ssl_certificate cert.pem;
158. ssl_certificate_key cert.key;
159. ssl_session_timeout 5m;
160. ssl_protocols SSLv2 SSLv3 TLSv1;
161. ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP;
162. ssl_prefer_server_ciphers on;
163. location / {
164. proxy_pass https://bsploginsvr;
165. include proxy_setting.conf;
166. }
167. access_log logs/login.log test_com;
168. }
169. #login.test.com for register
170. server {
171. listen 10.10.10.230:80;
172. server_name login.test.com;
173. location / {
174. proxy_pass http://bspregistersvr;
175. include proxy_setting.conf;
176. }
177. access_log logs/register.log test_com;
178. }
179.
180. }
181. <conf/proxy_setting.conf>
182. proxy_redirect off;
183. proxy_set_header Host $host;
184. proxy_set_header X-Real-IP $remote_addr;
185. proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
186. client_max_body_size 10m;
187. client_body_buffer_size 128k;
188. proxy_connect_timeout 90;
189. proxy_send_timeout 90;
190. proxy_read_timeout 90;
191. proxy_buffer_size 4k;
192. proxy_buffers 4 32k;
193. proxy_busy_buffers_size 64k;
194. proxy_temp_file_write_size 64k;
195. mod_proxy的例子：
196.
197. <VirtualHost *>
198. ServerName www.zxsv.com
199. ServerAdmin admin@zxsv.com
200. # reverse proxy setting
201. ProxyPass / http://www.zxsv.com:8080/
202. ProxyPassReverse / http://www.zxsv.com:8080/
203. # cache dir root
204. CacheRoot “/var/www/proxy”
205. # max cache storage
206. CacheSize 50000000
207. # hour: every 4 hour
208. CacheGcInterval 4
209. # max page expire time: hour
210. CacheMaxExpire 240
211. # Expire time = (now – last_modified) * CacheLastModifiedFactor
212. CacheLastModifiedFactor 0.1
213. # defalt expire tag: hour
214. CacheDefaultExpire 1
215. # force complete after precent of content retrived: 60-90%
216. CacheForceCompletion 80
217. CustomLog /usr/local/apache/logs/dev_access_log combined
218. </VirtualHost>
2. #user nobody;
3. worker_processes 4;
4. error_log logs/error.log crit;
5. pid logs/nginx.pid;
6. worker_rlimit_nofile 10240;
7. events {
8. use epoll;
9. worker_connections 51200;
10. }
11. http {
12. include mime.types;
13. default_type application/octet-stream;
14. sendfile on;
15. keepalive_timeout 65;
16. tcp_nodelay on;
17. # server pool
18. upstream bspfrontsvr {
19. server 10.10.10.224:80 weight=1;
20. server 10.10.10.221:80 weight=1;
21. }
22.
23. upstream bspimgsvr {
24. server 10.10.10.201:80 weight=1;
25. }
26.
27. upstream bspstylesvr {
28. server 10.10.10.202:80 weight=1;
29. }
30.
31. upstream bsphelpsvr {
32. server 10.10.10.204:80 weight=1;
33. }
34.
35. upstream bspwsisvr {
36. server 10.10.10.203:80 weight=1;
37. }
38.
39. upstream bspadminsvr {
40. server 10.10.10.222:80 weight=1;
41. }
42.
43. upstream bspbuyersvr {
44. server 10.10.10.223:80 weight=1;
45. }
46.
47. upstream bspsellersvr {
48. server 10.10.10.225:80 weight=1;
49. }
50. upstream bsploginsvr {
51. server 10.10.10.220:443 weight=1;
52. }
53. upstream bspregistersvr {
54. server 10.10.10.220:80 weight=1;
55. }
56. log_format test_com ‘$remote_addr – $remote_user [$time_local] “$request” ‘
57. ‘$status $body_bytes_sent “$http_referer” “$http_user_agent” ‘;
58. #——————————————————————–
59. #img.test.com
60. server {
61. listen 10.10.10.230:80;
62. server_name img.test.com;
63. location / {
64. proxy_pass http://bspimgsvr;
65. include proxy_setting.conf;
66. }
67. access_log logs/img.log test_com;
68. }
69.
70. #style.test.com
71. server {
72. listen 10.10.10.230:80;
73. server_name style.test.com;
74. location / {
75. proxy_pass http://bspstylesvr;
76. include proxy_setting.conf;
77. }
78. access_log logs/style.log test_com;
79. }
80.
81. #help.test.com
82. server {
83. listen 10.10.10.230:80;
84. server_name help.test.com;
85. location / {
86. proxy_pass http://bsphelpsvr;
87. include proxy_setting.conf;
88. }
89. access_log logs/help.log test_com;
90. }
91.
92. #admin.test.com
93. server {
94. listen 10.10.10.230:80;
95. server_name admin.test.com;
96. location / {
97. proxy_pass http://bspadminsvr;
98. include proxy_setting.conf;
99. }
100. access_log logs/admin.log test_com;
101. }
102.
103. #buyer.test.com
104. server {
105. listen 10.10.10.230:80;
106. server_name buyer.test.com;
107. location / {
108. proxy_pass http://bspbuyersvr;
109. include proxy_setting.conf;
110. }
111. access_log logs/buyer.log test_com;
112. }
113.
114. #seller.test.com
115. server {
116. listen 10.10.10.230:80;
117. server_name seller.test.com;
118. location / {
119. proxy_pass http://bspsellersvr;
120. include proxy_setting.conf;
121. }
122. access_log logs/seller.log test_com;
123. }
124. #wsi.test.com
125. server {
126. listen 10.10.10.230:80;
127. server_name wsi.test.com;
128. location / {
129. proxy_pass http://bspwsisvr;
130. include proxy_setting.conf;
131. }
132. access_log logs/wsi.log test_com;
133. }
134. #www.test.com
135. server {
136. listen 10.10.10.230:80;
137. server_name www.test.com *.test.com;
138. location ~ ^/NginxStatus/ {
139. stub_status on;
140. access_log off;
141. }
142. location / {
143. proxy_pass http://bspfrontsvr;
144. include proxy_setting.conf;
145. }
146. access_log logs/www.log test_com;
147. error_page 500 502 503 504 /50x.html;
148. location = /50x.html {
149. root html;
150. }
151. }
152. #login.test.com
153. server {
154. listen 10.10.10.230:443;
155. server_name login.test.com;
156. ssl on;
157. ssl_certificate cert.pem;
158. ssl_certificate_key cert.key;
159. ssl_session_timeout 5m;
160. ssl_protocols SSLv2 SSLv3 TLSv1;
161. ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP;
162. ssl_prefer_server_ciphers on;
163. location / {
164. proxy_pass https://bsploginsvr;
165. include proxy_setting.conf;
166. }
167. access_log logs/login.log test_com;
168. }
169. #login.test.com for register
170. server {
171. listen 10.10.10.230:80;
172. server_name login.test.com;
173. location / {
174. proxy_pass http://bspregistersvr;
175. include proxy_setting.conf;
176. }
177. access_log logs/register.log test_com;
178. }
179.
180. }
181. <conf/proxy_setting.conf>
182. proxy_redirect off;
183. proxy_set_header Host $host;
184. proxy_set_header X-Real-IP $remote_addr;
185. proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
186. client_max_body_size 10m;
187. client_body_buffer_size 128k;
188. proxy_connect_timeout 90;
189. proxy_send_timeout 90;
190. proxy_read_timeout 90;
191. proxy_buffer_size 4k;
192. proxy_buffers 4 32k;
193. proxy_busy_buffers_size 64k;
194. proxy_temp_file_write_size 64k;
195. mod_proxy的例子：
196.
197. <VirtualHost *>
198. ServerName www.zxsv.com
199. ServerAdmin admin@zxsv.com
200. # reverse proxy setting
201. ProxyPass / http://www.zxsv.com:8080/
202. ProxyPassReverse / http://www.zxsv.com:8080/
203. # cache dir root
204. CacheRoot “/var/www/proxy”
205. # max cache storage
206. CacheSize 50000000
207. # hour: every 4 hour
208. CacheGcInterval 4
209. # max page expire time: hour
210. CacheMaxExpire 240
211. # Expire time = (now – last_modified) * CacheLastModifiedFactor
212. CacheLastModifiedFactor 0.1
213. # defalt expire tag: hour
214. CacheDefaultExpire 1
215. # force complete after precent of content retrived: 60-90%
216. CacheForceCompletion 80
217. CustomLog /usr/local/apache/logs/dev_access_log combined
218. </VirtualHost>
而SQUID的例子我就不說明了，這方面網上有寫的太多，大家自己搜索一下
DNS輪詢：
BIND是一款開放源碼的DNS服務器軟件，這個要說起來就大了，自己搜索去，大家知道有這個東西就行了。
我知道的有chinacache 等大站就是這樣做的，說簡單點就是多服務器啦，把同一個頁面或文件緩存到不同的服務器上，按南北自動解析到相關的服務器中。
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