RFR (S) 8227370 Remove SharedPathsMiscInfo

[Ioi Lam]

Hi Jiangli and Calvin,

Thanks for the review. I've incorporated your comments in the following 
webrev:

http://cr.openjdk.java.net/~iklam/jdk14/8227370_remove_shared_misc_info.v03/
http://cr.openjdk.java.net/~iklam/jdk14/8227370_remove_shared_misc_info.v03-delta/

Please take a look.
Thanks
- Ioi


On 8/26/19 5:56 PM, Jiangli Zhou wrote:
> Nice cleanup! Just some minor issues/suggestions below.
> - src/hotspot/share/classfile/classLoaderExt.cpp
>   213         trace_class_path("library = ", libname);
> 214 if (!ClassLoader::update_class_path_entry_list(libname, true, 
> false, true /* from_class_path_attr */)) {
> 215 FileMapInfo::record_non_existent_class_path_entry(libname);
> 216 }
> It might be useful to do trace_class_path() after 
> update_class_path_entry_list, so the trace message can indicate if the 
> directory exists or not.
> - src/hotspot/share/memory/filemap.cpp
> 843 bool FileMapInfo::validate_non_existent_class_paths() const {
> 844 assert(UseSharedSpaces, "runtime only");
> 845 for (int i = _header->_app_module_paths_start_index + 
> _header->_num_module_paths;
> 846 i < get_number_of_shared_paths();
> 847 i++) {
> 848 SharedClassPathEntry* ent = shared_path(i);
> 849 if (!ent->check_non_existent()) {
> 850 fail_continue("file must not exist: %s", ent->name());
> 851 return false;
> 852 }
> 853 }
> 854 return true;
> If check_non_existent() returns false, it could still use the archived 
> JDK classes at runtime and only invalidate the archived application 
> classes. So we don't lose all performance benefit.
>   160   // All of these entries must be JAR files. The dumping process would fail if a non-empty
>   161   // directory was specified in the classpaths. If an empty directory was specified
>   162   // it is checked by the _paths_misc_info as described above.
>   228   char* _paths_misc_info;
> Could you please cleanup above _paths_misc_info references?
> Thanks!
> Jiangli
>
> On Fri, Aug 23, 2019 at 4:56 PM Ioi Lam <ioi.lam at oracle.com 
> <mailto:ioi.lam at oracle.com>> wrote:
>
>     Hi Jiangli,
>
>     Thanks for the info. I have added code and test for non-existent
>     files specified in Class-Path:.
>
>     http://cr.openjdk.java.net/~iklam/jdk14/8227370_remove_shared_misc_info.v02/
>
>     I also consolidated some of the duplicated code in
>     FileMapInfo::add_shared_classpaths().
>
>     Thanks
>     - Ioi
>
>
>     On 8/23/19 8:47 AM, Jiangli Zhou wrote:
>>     Hi,
>>
>>     It's not a complete code review yet. One good point that Calvin
>>     brought up during the code review email discussion for the
>>     previous related change was that runtime needs to check the
>>     non-existing JAR entries specified via the Class-Path header in
>>     manifest. Could you please verify those cases are handled
>>     properly with the change? Thanks.
>>
>>     Regards,
>>     Jiangli
>>
>>     On Thu, Aug 22, 2019 at 8:28 AM Ioi Lam <ioi.lam at oracle.com
>>     <mailto:ioi.lam at oracle.com>> wrote:
>>
>>         https://bugs.openjdk.java.net/browse/JDK-8227370
>>         http://cr.openjdk.java.net/~iklam/jdk14/8227370_remove_shared_misc_info.v01/
>>
>>         For the 3 types of items stored in SharedPathsMiscInfo
>>
>>         BOOT_PATH/APP_PATH:
>>
>>         These are used only for tracing. I reimplemented the tracing
>>         functionality in FileMapInfo::log_paths()
>>
>>         NON_EXIST:
>>
>>         It turns out we don't need to keep track of non-existent
>>         paths from the
>>         dump-time path.  We can simply eliminate all the non-existent
>>         paths from
>>         both the dump-time and runtime paths, and check that the
>>         remaining files
>>         match. E.g.,
>>
>>         dump: -cp a.jar:NE1:NE2:b.jar
>>         run 1: -cp NE3:a.jar:NE4:b.jar
>>         run 2: -cp x.jar:NE4:b.jar
>>
>>         after elimination:
>>
>>         dump = a.jar:b.jar
>>         run 1 = a.jar:b.jar -> matched
>>         run 2 = x.jar:b.jar -> mismatched
>>
>>         The dump-time elimination was already done in
>>         ClassLoader::update_class_path_entry_list().
>>         The run-time elimination was already done in
>>         FileMapInfo::create_path_array().
>>
>>         So essentially I just tied things together and wrote a few
>>         more test cases
>>         in NonExistClasspath.java
>>
>>
>>         Testing: hs-tier{1,2,3}
>>
>