{"id":195,"date":"2008-01-08T22:24:21","date_gmt":"2008-01-08T22:24:21","guid":{"rendered":"https:\/\/kari.world.ikari.fi\/2008\/01\/08\/detecting-from-where-code-is-called\/"},"modified":"2008-01-08T22:24:21","modified_gmt":"2008-01-08T22:24:21","slug":"detecting-from-where-code-is-called","status":"publish","type":"post","link":"https:\/\/kari.world.ikari.fi\/?p=195","title":{"rendered":"Detecting from where code is called"},"content":{"rendered":"

Detect if current piece of code is called by own classes:
\n
\n[code lang=”java”]
\n\/**
\n * @return True if current execution points originates from own classes
\n *\/
\npublic static boolean isOwn() {
\n StackTraceElement[] stack = Thread.currentThread().getStackTrace();<\/p>\n

int len = stack.length;
\n for (int i = 2; i < len; i++) {\n if (stack[i].getClassName().startsWith(\"org.kari.\")) {\n return true;\n }\n }\n\n return false;\n}\n[\/code]\n\n\n\n

Detect if StringBuilder is called by own classes:
\n
\n[code lang=”java”]
\n\/**
\n * @return true if StringBuilder is directly called by own class
\n *\/
\npublic static boolean isImmediateOwn() {
\n StackTraceElement[] stack = Thread.currentThread().getStackTrace();<\/p>\n

int index = 2;
\n int len = stack.length;<\/p>\n

for (; index < len; index++) {\n String className = stack[index].getClassName();\n if (className.startsWith(\"org.kari.\")) {\n return true;\n }\n if (!(className.equals(\"java.lang.AbstractStringBuilder\")\n || className.equals(\"java.lang.StringBuilder\")) )\n {\n return false;\n }\n }\n\n return false;\n}\n[\/code]\n\n\n\n

And now actual utilitization in Eclipse.<\/p>\n

    \n
  1. Open AbstractStringBuilder -class<\/li>\n
  2. Add breakpoint into beginning of expandCapacity() -method<\/li>\n
  3. Paste following code as breakpoint condition:
    \n[code lang=”java”]
    \nStackTraceElement[] stack = Thread.currentThread().getStackTrace();<\/p>\n

    int index = 2;
    \nint len = stack.length;<\/p>\n

    for (; index < len; index++) {\n String className = stack[index].getClassName();\n if (className.startsWith(\"org.kari.\")) {\n return true;\n }\n if (!(className.equals(\"java.lang.AbstractStringBuilder\")\n || className.equals(\"java.lang.StringBuilder\")) )\n {\n return false;\n }\n}\nreturn false;\n[\/code]\n<\/li>\n<\/ol>\n

    Now Eclipse will hit the breakpoint whenever StringBuilder is expanded as a direct call from application logic. So what is the point of this exercise. Answer is the curiosity of analyzing how much String trashing application logic is performing.<\/p>\n

    Sadly just calling directly org.kari.util.ClassUtil.isImmediateOwn()from breakpoint does not work, but logic must be copy-pasted into breakpoint condition.<\/p>\n

    However, since we want to simplify debugging, and simply write this:
    \n[code lang=”java”]
    \norg.kari.util.ClassUtil.isImmediateOwn()
    \n[\/code]<\/p>\n

    Reason why it doesn’t work is that when break point is placed into some class coming from ”bootclasspath”, java class loading mechanism prevents access into this rogue ”org.kari.util.ClassUtil” -class. However, problem can be worked around by adjusting bootstrap class path:<\/p>\n

      \n
    1. Create new folder into project, named ”bootclasses”<\/li>\n
    2. Take: Run -> Open Debug Dialog…<\/li>\n
    3. Select ”Classpath” -tab<\/li>\n
    4. Select ”Bootstrap entries”<\/li>\n
    5. Select ”Advanced…”<\/li>\n
    6. Select ”Add Folders”<\/li>\n
    7. Select ”Project\/bootclasses”<\/li>\n
    8. Go into command line, and copy org.kari.util.ClassUtil from Project\/bin into Project\/bootclasses<\/li>\n<\/ol>\n

      After this org.kari.util.ClassUtil.isImmediateOwn()<\/b> will work as breakpoint for system classes.<\/p>\n

      And our final breakpoint condition is then
      \n[code lang=”java”]
      \narg0 > 50 && org.kari.util.ClassUtil.isImmediateOwn()
      \n[\/code]<\/p>\n

      Note ”arg0” must be used to refer ”minimumCapacity” argument of expandCapacity() -method.<\/p>\n

      PS. Simple breakpoint without condition in expandCapasity() -method, shows that AWT\/Swing are doing lots of reduntant String trashing internally.<\/p>\n","protected":false},"excerpt":{"rendered":"

      Detect if current piece of code is called by own classes: [code lang=”java”] \/** * @return True if current execution points originates from own classes *\/ public static boolean isOwn() { StackTraceElement[] stack = Thread.currentThread().getStackTrace(); int len = stack.length; for (int i = 2; i < len; i++) { if (stack[i].getClassName().startsWith(\"org.kari.\")) { return true; }...\n<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-195","post","type-post","status-publish","format-standard","hentry","category-java"],"_links":{"self":[{"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/posts\/195","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=195"}],"version-history":[{"count":0,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=\/wp\/v2\/posts\/195\/revisions"}],"wp:attachment":[{"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=195"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=195"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kari.world.ikari.fi\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=195"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}