Thu, 21 Aug 2014 13:57:51 -0700
8046070: Class Data Sharing clean up and refactoring
Summary: Cleaned up CDS to be more configurable, maintainable and extensible
Reviewed-by: dholmes, coleenp, acorn, mchung
1 /*
2 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
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23 */
25 #ifndef SHARE_VM_MEMORY_FILEMAP_HPP
26 #define SHARE_VM_MEMORY_FILEMAP_HPP
28 #include "memory/metaspaceShared.hpp"
29 #include "memory/metaspace.hpp"
31 // Layout of the file:
32 // header: dump of archive instance plus versioning info, datestamp, etc.
33 // [magic # = 0xF00BABA2]
34 // ... padding to align on page-boundary
35 // read-write space from CompactingPermGenGen
36 // read-only space from CompactingPermGenGen
37 // misc data (block offset table, string table, symbols, dictionary, etc.)
38 // tag(666)
40 static const int JVM_IDENT_MAX = 256;
42 class Metaspace;
44 class SharedClassPathEntry VALUE_OBJ_CLASS_SPEC {
45 public:
46 const char *_name;
47 time_t _timestamp; // jar timestamp, 0 if is directory
48 long _filesize; // jar file size, -1 if is directory
49 bool is_dir() {
50 return _filesize == -1;
51 }
52 };
54 class FileMapInfo : public CHeapObj<mtInternal> {
55 private:
56 friend class ManifestStream;
57 enum {
58 _invalid_version = -1,
59 _current_version = 2
60 };
62 bool _file_open;
63 int _fd;
64 long _file_offset;
66 private:
67 static SharedClassPathEntry* _classpath_entry_table;
68 static int _classpath_entry_table_size;
69 static size_t _classpath_entry_size;
70 static bool _validating_classpath_entry_table;
72 // FileMapHeader describes the shared space data in the file to be
73 // mapped. This structure gets written to a file. It is not a class, so
74 // that the compilers don't add any compiler-private data to it.
76 public:
77 struct FileMapHeaderBase : public CHeapObj<mtClass> {
78 virtual bool validate() = 0;
79 virtual void populate(FileMapInfo* info, size_t alignment) = 0;
80 };
81 struct FileMapHeader : FileMapHeaderBase {
82 // Use data() and data_size() to memcopy to/from the FileMapHeader. We need to
83 // avoid read/writing the C++ vtable pointer.
84 static size_t data_size();
85 char* data() {
86 return ((char*)this) + sizeof(FileMapHeaderBase);
87 }
89 int _magic; // identify file type.
90 int _version; // (from enum, above.)
91 size_t _alignment; // how shared archive should be aligned
92 int _obj_alignment; // value of ObjectAlignmentInBytes
94 struct space_info {
95 int _file_offset; // sizeof(this) rounded to vm page size
96 char* _base; // copy-on-write base address
97 size_t _capacity; // for validity checking
98 size_t _used; // for setting space top on read
99 bool _read_only; // read only space?
100 bool _allow_exec; // executable code in space?
101 } _space[MetaspaceShared::n_regions];
103 // The following fields are all sanity checks for whether this archive
104 // will function correctly with this JVM and the bootclasspath it's
105 // invoked with.
106 char _jvm_ident[JVM_IDENT_MAX]; // identifier for jvm
108 // The _paths_misc_info is a variable-size structure that records "miscellaneous"
109 // information during dumping. It is generated and validated by the
110 // SharedPathsMiscInfo class. See SharedPathsMiscInfo.hpp and sharedClassUtil.hpp for
111 // detailed description.
112 //
113 // The _paths_misc_info data is stored as a byte array in the archive file header,
114 // immediately after the _header field. This information is used only when
115 // checking the validity of the archive and is deallocated after the archive is loaded.
116 //
117 // Note that the _paths_misc_info does NOT include information for JAR files
118 // that existed during dump time. Their information is stored in _classpath_entry_table.
119 int _paths_misc_info_size;
121 // The following is a table of all the class path entries that were used
122 // during dumping. At run time, we require these files to exist and have the same
123 // size/modification time, or else the archive will refuse to load.
124 //
125 // All of these entries must be JAR files. The dumping process would fail if a non-empty
126 // directory was specified in the classpaths. If an empty directory was specified
127 // it is checked by the _paths_misc_info as described above.
128 //
129 // FIXME -- if JAR files in the tail of the list were specified but not used during dumping,
130 // they should be removed from this table, to save space and to avoid spurious
131 // loading failures during runtime.
132 int _classpath_entry_table_size;
133 size_t _classpath_entry_size;
134 SharedClassPathEntry* _classpath_entry_table;
136 virtual bool validate();
137 virtual void populate(FileMapInfo* info, size_t alignment);
138 };
140 FileMapHeader * _header;
142 const char* _full_path;
143 char* _paths_misc_info;
145 static FileMapInfo* _current_info;
147 bool init_from_file(int fd);
148 void align_file_position();
149 bool validate_header_impl();
151 public:
152 FileMapInfo();
153 ~FileMapInfo();
155 static int current_version() { return _current_version; }
156 void populate_header(size_t alignment);
157 bool validate_header();
158 void invalidate();
159 int version() { return _header->_version; }
160 size_t alignment() { return _header->_alignment; }
161 size_t space_capacity(int i) { return _header->_space[i]._capacity; }
162 char* region_base(int i) { return _header->_space[i]._base; }
163 struct FileMapHeader* header() { return _header; }
165 static FileMapInfo* current_info() {
166 CDS_ONLY(return _current_info;)
167 NOT_CDS(return NULL;)
168 }
170 static void assert_mark(bool check);
172 // File manipulation.
173 bool initialize() NOT_CDS_RETURN_(false);
174 bool open_for_read();
175 void open_for_write();
176 void write_header();
177 void write_space(int i, Metaspace* space, bool read_only);
178 void write_region(int region, char* base, size_t size,
179 size_t capacity, bool read_only, bool allow_exec);
180 void write_bytes(const void* buffer, int count);
181 void write_bytes_aligned(const void* buffer, int count);
182 char* map_region(int i);
183 void unmap_region(int i);
184 void close();
185 bool is_open() { return _file_open; }
186 ReservedSpace reserve_shared_memory();
188 // JVM/TI RedefineClasses() support:
189 // Remap the shared readonly space to shared readwrite, private.
190 bool remap_shared_readonly_as_readwrite();
192 // Errors.
193 static void fail_stop(const char *msg, ...);
194 static void fail_continue(const char *msg, ...);
196 // Return true if given address is in the mapped shared space.
197 bool is_in_shared_space(const void* p) NOT_CDS_RETURN_(false);
198 void print_shared_spaces() NOT_CDS_RETURN;
200 static size_t shared_spaces_size() {
201 return align_size_up(SharedReadOnlySize + SharedReadWriteSize +
202 SharedMiscDataSize + SharedMiscCodeSize,
203 os::vm_allocation_granularity());
204 }
206 // Stop CDS sharing and unmap CDS regions.
207 static void stop_sharing_and_unmap(const char* msg);
209 static void allocate_classpath_entry_table();
210 bool validate_classpath_entry_table();
212 static SharedClassPathEntry* shared_classpath(int index) {
213 char* p = (char*)_classpath_entry_table;
214 p += _classpath_entry_size * index;
215 return (SharedClassPathEntry*)p;
216 }
217 static const char* shared_classpath_name(int index) {
218 return shared_classpath(index)->_name;
219 }
221 static int get_number_of_share_classpaths() {
222 return _classpath_entry_table_size;
223 }
224 };
226 #endif // SHARE_VM_MEMORY_FILEMAP_HPP