{"id":1491,"date":"2017-03-12T22:04:20","date_gmt":"2017-03-12T14:04:20","guid":{"rendered":"http:\/\/coderbee.net\/?p=1491"},"modified":"2017-07-03T23:16:33","modified_gmt":"2017-07-03T15:16:33","slug":"%e5%9f%ba%e4%ba%8e%e6%95%b0%e6%8d%ae%e5%ba%93%e7%9a%84%e4%b9%90%e8%a7%82%e9%94%81","status":"publish","type":"post","link":"https:\/\/coderbee.net\/index.php\/concurrent\/20170312\/1491","title":{"rendered":"\u57fa\u4e8e\u6570\u636e\u5e93\u7684\u4e50\u89c2\u9501"},"content":{"rendered":"<p>\u6d89\u53ca\u6d89\u53ca\u6570\u636e\u5e93\u7684\u9ad8\u5e76\u53d1\u89e3\u51b3\u65b9\u6848\u4e00\u822c\u90fd\u4f1a\u63d0\u5230\u4e50\u89c2\u9501\u3002<\/p>\n<p>\u4e50\u89c2\u9501\uff1a\u5728\u63d0\u4ea4\u6570\u636e\u66f4\u65b0\u4e4b\u524d\uff0c\u6bcf\u4e2a\u4e8b\u52a1\u4f1a\u5148\u68c0\u67e5\u5728\u8be5\u4e8b\u52a1\u8bfb\u53d6\u6570\u636e\u540e\uff0c\u6709\u6ca1\u6709\u5176\u4ed6\u4e8b\u52a1\u53c8\u4fee\u6539\u4e86\u8be5\u6570\u636e\u3002\u5982\u679c\u5176\u4ed6\u4e8b\u52a1\u6709\u66f4\u65b0\u7684\u8bdd\uff0c\u6b63\u5728\u63d0\u4ea4\u7684\u4e8b\u52a1\u4f1a\u8fdb\u884c\u56de\u6eda\u3002<\/p>\n<p>\u5229\u7528\u6570\u636e\u5e93\u5b9e\u73b0\u4e50\u89c2\u9501\u7684\u4f2a\u4ee3\u7801\uff1a<\/p>\n<pre><code class=\"java\">Connection conn = DriverManager.getConnection(url, user, password);\nconn.setAutoCommit(false);\nStatement stmt = conn.createStatement();\n\/\/ step 1\nint oldVersion = getOldVersion(stmt);\n\n\/\/ step 2\n\/\/ \u7528\u8fd9\u4e2a\u6570\u636e\u5e93\u8fde\u63a5\u505a\u5176\u4ed6\u7684\u903b\u8f91\n\n\/\/ step 3 \u53ef\u7528\u9884\u7f16\u8bd1\u8bed\u53e5\nint i = stmt.executeUpdate(\n        \"update optimistic_lock set version = \" + (oldVersion + 1) + \" where version = \" + oldVersion);\n\n\/\/ step 4\nif (i &gt; 0) {\n    conn.commit(); \/\/ \u66f4\u65b0\u6210\u529f\u8868\u660e\u6570\u636e\u6ca1\u6709\u88ab\u4fee\u6539\uff0c\u63d0\u4ea4\u4e8b\u52a1\u3002\n} else {\n    conn.rollback(); \/\/ \u66f4\u65b0\u5931\u8d25\uff0c\u6570\u636e\u88ab\u4fee\u6539\uff0c\u56de\u6eda\u3002\n}\n<\/code><\/pre>\n<p>\u6ce8\u610f\u4e8b\u9879\uff1a<\/p>\n<ul>\n<li>\u524d\u9762\u4f2a\u4ee3\u7801\u7684 step 3 \u548c 4 \u5e94\u5728\u5b58\u50a8\u8fc7\u7a0b\u91cc\u5b8c\u6210\uff0c\u9632\u6b62 step 3 \u5b8c\u6210\u540e\uff0c\u7531\u4e8e GC \u6216\u7f51\u7edc\u963b\u585e\u5bfc\u81f4 step 4 \u5ef6\u8fdf\u6267\u884c\uff0c\u6b64\u65f6 \u4e50\u89c2\u9501\u7684\u8bb0\u5f55\u88ab\u6570\u636e\u5e93\u9501\u5b9a\uff0c\u5176\u4ed6\u8bf7\u6c42\u8981\u8fdb\u884c\u66f4\u65b0\u53ea\u80fd\u7b49\u5f85\uff0c\u88ab\u963b\u585e\u3002<br \/>\n\u53ef\u4ee5\u7528\u5b58\u50a8\u8fc7\u7a0b\u6765\u66ff\u4ee3\u540e\u9762\u7684\u4e24\u6b65\uff0c\u6216\u8005\u6574\u4e2a\u903b\u8f91\u90fd\u7528\u5b58\u50a8\u8fc7\u7a0b\u5b9e\u73b0\uff1a<\/li>\n<\/ul>\n<pre><code class=\"sql\">delimiter $$\n\ncreate procedure sp_update_version (newVersion int, oldVersion int) begin\n    update optimistic_lock t set t.version = newVersion where t.version = oldVersion;\n\n    if row_count() &gt; 0 then\n        commit;\n    else\n        rollback;\n    end if;\nend $$\n<\/code><\/pre>\n<p>\u4e50\u89c2\u9501\u7684\u7f3a\u70b9\uff1a<\/p>\n<ul>\n<li>\u4f1a\u5e26\u6765\u5927\u6570\u91cf\u7684\u65e0\u6548\u66f4\u65b0\u8bf7\u6c42\u3001\u4e8b\u52a1\u56de\u6eda\uff0c\u7ed9DB\u9020\u6210\u4e0d\u5fc5\u8981\u7684\u989d\u5916\u538b\u529b\u3002<\/li>\n<li>\u65e0\u6cd5\u4fdd\u8bc1\u5148\u5230\u5148\u5f97\uff0c\u540e\u9762\u7684\u8bf7\u6c42\u53ef\u80fd\u7531\u4e8e\u5e76\u53d1\u538b\u529b\u5c0f\u4e86\u53cd\u800c\u6709\u53ef\u80fd\u5904\u7406\u6210\u529f\u3002<\/li>\n<\/ul>\n<hr\/>\n<p>\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u5fae\u4fe1\u516c\u4f17\u53f7: <strong>coderbee\u7b14\u8bb0<\/strong>\uff0c\u53ef\u4ee5\u66f4\u53ca\u65f6\u56de\u590d\u4f60\u7684\u8ba8\u8bba\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"258\" height=\"258\" src=\"https:\/\/coderbee.net\/wp-content\/uploads\/2019\/01\/coderbee-note.jpg\" class=\"alignnone size-full wp-image-1707\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6d89\u53ca\u6d89\u53ca\u6570\u636e\u5e93\u7684\u9ad8\u5e76\u53d1\u89e3\u51b3\u65b9\u6848\u4e00\u822c\u90fd\u4f1a\u63d0\u5230\u4e50\u89c2\u9501\u3002 \u4e50\u89c2\u9501\uff1a\u5728\u63d0\u4ea4\u6570\u636e\u66f4\u65b0\u4e4b\u524d\uff0c &hellip; <a href=\"https:\/\/coderbee.net\/index.php\/concurrent\/20170312\/1491\">\u7ee7\u7eed\u9605\u8bfb <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[121],"tags":[],"_links":{"self":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1491"}],"collection":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/comments?post=1491"}],"version-history":[{"count":2,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1491\/revisions"}],"predecessor-version":[{"id":1493,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1491\/revisions\/1493"}],"wp:attachment":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/media?parent=1491"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/categories?post=1491"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/tags?post=1491"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}