Fri, 25 Jan 2013 15:06:18 -0500
6479360: PrintClassHistogram improvements
Summary: jcmd <pid> GC.class_stats (UnlockDiagnosticVMOptions)
Reviewed-by: coleenp, hseigel, sla, acorn
Contributed-by: ioi.lam@oracle.com
1 /*
2 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
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
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/altHashing.hpp"
29 #include "memory/filemap.hpp"
30 #include "runtime/arguments.hpp"
31 #include "runtime/java.hpp"
32 #include "runtime/os.hpp"
33 #include "services/memTracker.hpp"
34 #include "utilities/defaultStream.hpp"
36 # include <sys/stat.h>
37 # include <errno.h>
39 #ifndef O_BINARY // if defined (Win32) use binary files.
40 #define O_BINARY 0 // otherwise do nothing.
41 #endif
44 extern address JVM_FunctionAtStart();
45 extern address JVM_FunctionAtEnd();
47 // Complain and stop. All error conditions occurring during the writing of
48 // an archive file should stop the process. Unrecoverable errors during
49 // the reading of the archive file should stop the process.
51 static void fail(const char *msg, va_list ap) {
52 // This occurs very early during initialization: tty is not initialized.
53 jio_fprintf(defaultStream::error_stream(),
54 "An error has occurred while processing the"
55 " shared archive file.\n");
56 jio_vfprintf(defaultStream::error_stream(), msg, ap);
57 jio_fprintf(defaultStream::error_stream(), "\n");
58 vm_exit_during_initialization("Unable to use shared archive.", NULL);
59 }
62 void FileMapInfo::fail_stop(const char *msg, ...) {
63 va_list ap;
64 va_start(ap, msg);
65 fail(msg, ap); // Never returns.
66 va_end(ap); // for completeness.
67 }
70 // Complain and continue. Recoverable errors during the reading of the
71 // archive file may continue (with sharing disabled).
72 //
73 // If we continue, then disable shared spaces and close the file.
75 void FileMapInfo::fail_continue(const char *msg, ...) {
76 va_list ap;
77 va_start(ap, msg);
78 if (RequireSharedSpaces) {
79 fail(msg, ap);
80 }
81 va_end(ap);
82 UseSharedSpaces = false;
83 close();
84 }
86 // Fill in the fileMapInfo structure with data about this VM instance.
88 // This method copies the vm version info into header_version. If the version is too
89 // long then a truncated version, which has a hash code appended to it, is copied.
90 //
91 // Using a template enables this method to verify that header_version is an array of
92 // length JVM_IDENT_MAX. This ensures that the code that writes to the CDS file and
93 // the code that reads the CDS file will both use the same size buffer. Hence, will
94 // use identical truncation. This is necessary for matching of truncated versions.
95 template <int N> static void get_header_version(char (&header_version) [N]) {
96 assert(N == JVM_IDENT_MAX, "Bad header_version size");
98 const char *vm_version = VM_Version::internal_vm_info_string();
99 const int version_len = (int)strlen(vm_version);
101 if (version_len < (JVM_IDENT_MAX-1)) {
102 strcpy(header_version, vm_version);
104 } else {
105 // Get the hash value. Use a static seed because the hash needs to return the same
106 // value over multiple jvm invocations.
107 unsigned int hash = AltHashing::murmur3_32(8191, (const jbyte*)vm_version, version_len);
109 // Truncate the ident, saving room for the 8 hex character hash value.
110 strncpy(header_version, vm_version, JVM_IDENT_MAX-9);
112 // Append the hash code as eight hex digits.
113 sprintf(&header_version[JVM_IDENT_MAX-9], "%08x", hash);
114 header_version[JVM_IDENT_MAX-1] = 0; // Null terminate.
115 }
116 }
118 void FileMapInfo::populate_header(size_t alignment) {
119 _header._magic = 0xf00baba2;
120 _header._version = _current_version;
121 _header._alignment = alignment;
122 _header._obj_alignment = ObjectAlignmentInBytes;
124 // The following fields are for sanity checks for whether this archive
125 // will function correctly with this JVM and the bootclasspath it's
126 // invoked with.
128 // JVM version string ... changes on each build.
129 get_header_version(_header._jvm_ident);
131 // Build checks on classpath and jar files
132 _header._num_jars = 0;
133 ClassPathEntry *cpe = ClassLoader::classpath_entry(0);
134 for ( ; cpe != NULL; cpe = cpe->next()) {
136 if (cpe->is_jar_file()) {
137 if (_header._num_jars >= JVM_SHARED_JARS_MAX) {
138 fail_stop("Too many jar files to share.", NULL);
139 }
141 // Jar file - record timestamp and file size.
142 struct stat st;
143 const char *path = cpe->name();
144 if (os::stat(path, &st) != 0) {
145 // If we can't access a jar file in the boot path, then we can't
146 // make assumptions about where classes get loaded from.
147 fail_stop("Unable to open jar file %s.", path);
148 }
149 _header._jar[_header._num_jars]._timestamp = st.st_mtime;
150 _header._jar[_header._num_jars]._filesize = st.st_size;
151 _header._num_jars++;
152 } else {
154 // If directories appear in boot classpath, they must be empty to
155 // avoid having to verify each individual class file.
156 const char* name = ((ClassPathDirEntry*)cpe)->name();
157 if (!os::dir_is_empty(name)) {
158 fail_stop("Boot classpath directory %s is not empty.", name);
159 }
160 }
161 }
162 }
165 // Read the FileMapInfo information from the file.
167 bool FileMapInfo::init_from_file(int fd) {
169 size_t n = read(fd, &_header, sizeof(struct FileMapHeader));
170 if (n != sizeof(struct FileMapHeader)) {
171 fail_continue("Unable to read the file header.");
172 return false;
173 }
174 if (_header._version != current_version()) {
175 fail_continue("The shared archive file has the wrong version.");
176 return false;
177 }
178 _file_offset = (long)n;
179 return true;
180 }
183 // Read the FileMapInfo information from the file.
184 bool FileMapInfo::open_for_read() {
185 _full_path = Arguments::GetSharedArchivePath();
186 int fd = open(_full_path, O_RDONLY | O_BINARY, 0);
187 if (fd < 0) {
188 if (errno == ENOENT) {
189 // Not locating the shared archive is ok.
190 fail_continue("Specified shared archive not found.");
191 } else {
192 fail_continue("Failed to open shared archive file (%s).",
193 strerror(errno));
194 }
195 return false;
196 }
198 _fd = fd;
199 _file_open = true;
200 return true;
201 }
204 // Write the FileMapInfo information to the file.
206 void FileMapInfo::open_for_write() {
207 _full_path = Arguments::GetSharedArchivePath();
208 if (PrintSharedSpaces) {
209 tty->print_cr("Dumping shared data to file: ");
210 tty->print_cr(" %s", _full_path);
211 }
213 // Remove the existing file in case another process has it open.
214 remove(_full_path);
215 #ifdef _WINDOWS // if 0444 is used on Windows, then remove() will fail.
216 int fd = open(_full_path, O_RDWR | O_CREAT | O_TRUNC | O_BINARY, 0744);
217 #else
218 int fd = open(_full_path, O_RDWR | O_CREAT | O_TRUNC | O_BINARY, 0444);
219 #endif
220 if (fd < 0) {
221 fail_stop("Unable to create shared archive file %s.", _full_path);
222 }
223 _fd = fd;
224 _file_offset = 0;
225 _file_open = true;
226 }
229 // Write the header to the file, seek to the next allocation boundary.
231 void FileMapInfo::write_header() {
232 write_bytes_aligned(&_header, sizeof(FileMapHeader));
233 }
236 // Dump shared spaces to file.
238 void FileMapInfo::write_space(int i, Metaspace* space, bool read_only) {
239 align_file_position();
240 size_t used = space->used_words(Metaspace::NonClassType) * BytesPerWord;
241 size_t capacity = space->capacity_words(Metaspace::NonClassType) * BytesPerWord;
242 struct FileMapInfo::FileMapHeader::space_info* si = &_header._space[i];
243 write_region(i, (char*)space->bottom(), used, capacity, read_only, false);
244 }
247 // Dump region to file.
249 void FileMapInfo::write_region(int region, char* base, size_t size,
250 size_t capacity, bool read_only,
251 bool allow_exec) {
252 struct FileMapInfo::FileMapHeader::space_info* si = &_header._space[region];
254 if (_file_open) {
255 guarantee(si->_file_offset == _file_offset, "file offset mismatch.");
256 if (PrintSharedSpaces) {
257 tty->print_cr("Shared file region %d: 0x%6x bytes, addr " INTPTR_FORMAT
258 " file offset 0x%6x", region, size, base, _file_offset);
259 }
260 } else {
261 si->_file_offset = _file_offset;
262 }
263 si->_base = base;
264 si->_used = size;
265 si->_capacity = capacity;
266 si->_read_only = read_only;
267 si->_allow_exec = allow_exec;
268 write_bytes_aligned(base, (int)size);
269 }
272 // Dump bytes to file -- at the current file position.
274 void FileMapInfo::write_bytes(const void* buffer, int nbytes) {
275 if (_file_open) {
276 int n = ::write(_fd, buffer, nbytes);
277 if (n != nbytes) {
278 // It is dangerous to leave the corrupted shared archive file around,
279 // close and remove the file. See bug 6372906.
280 close();
281 remove(_full_path);
282 fail_stop("Unable to write to shared archive file.", NULL);
283 }
284 }
285 _file_offset += nbytes;
286 }
289 // Align file position to an allocation unit boundary.
291 void FileMapInfo::align_file_position() {
292 long new_file_offset = align_size_up(_file_offset, os::vm_allocation_granularity());
293 if (new_file_offset != _file_offset) {
294 _file_offset = new_file_offset;
295 if (_file_open) {
296 // Seek one byte back from the target and write a byte to insure
297 // that the written file is the correct length.
298 _file_offset -= 1;
299 if (lseek(_fd, _file_offset, SEEK_SET) < 0) {
300 fail_stop("Unable to seek.", NULL);
301 }
302 char zero = 0;
303 write_bytes(&zero, 1);
304 }
305 }
306 }
309 // Dump bytes to file -- at the current file position.
311 void FileMapInfo::write_bytes_aligned(const void* buffer, int nbytes) {
312 align_file_position();
313 write_bytes(buffer, nbytes);
314 align_file_position();
315 }
318 // Close the shared archive file. This does NOT unmap mapped regions.
320 void FileMapInfo::close() {
321 if (_file_open) {
322 if (::close(_fd) < 0) {
323 fail_stop("Unable to close the shared archive file.");
324 }
325 _file_open = false;
326 _fd = -1;
327 }
328 }
331 // JVM/TI RedefineClasses() support:
332 // Remap the shared readonly space to shared readwrite, private.
333 bool FileMapInfo::remap_shared_readonly_as_readwrite() {
334 struct FileMapInfo::FileMapHeader::space_info* si = &_header._space[0];
335 if (!si->_read_only) {
336 // the space is already readwrite so we are done
337 return true;
338 }
339 size_t used = si->_used;
340 size_t size = align_size_up(used, os::vm_allocation_granularity());
341 if (!open_for_read()) {
342 return false;
343 }
344 char *base = os::remap_memory(_fd, _full_path, si->_file_offset,
345 si->_base, size, false /* !read_only */,
346 si->_allow_exec);
347 close();
348 if (base == NULL) {
349 fail_continue("Unable to remap shared readonly space (errno=%d).", errno);
350 return false;
351 }
352 if (base != si->_base) {
353 fail_continue("Unable to remap shared readonly space at required address.");
354 return false;
355 }
356 si->_read_only = false;
357 return true;
358 }
360 // Map the whole region at once, assumed to be allocated contiguously.
361 ReservedSpace FileMapInfo::reserve_shared_memory() {
362 struct FileMapInfo::FileMapHeader::space_info* si = &_header._space[0];
363 char* requested_addr = si->_base;
364 size_t alignment = os::vm_allocation_granularity();
366 size_t size = align_size_up(SharedReadOnlySize + SharedReadWriteSize +
367 SharedMiscDataSize + SharedMiscCodeSize,
368 alignment);
370 // Reserve the space first, then map otherwise map will go right over some
371 // other reserved memory (like the code cache).
372 ReservedSpace rs(size, alignment, false, requested_addr);
373 if (!rs.is_reserved()) {
374 fail_continue(err_msg("Unable to reserved shared space at required address " INTPTR_FORMAT, requested_addr));
375 return rs;
376 }
377 // the reserved virtual memory is for mapping class data sharing archive
378 MemTracker::record_virtual_memory_type((address)rs.base(), mtClassShared);
380 return rs;
381 }
383 // Memory map a region in the address space.
384 static const char* shared_region_name[] = { "ReadOnly", "ReadWrite", "MiscData", "MiscCode"};
386 char* FileMapInfo::map_region(int i) {
387 struct FileMapInfo::FileMapHeader::space_info* si = &_header._space[i];
388 size_t used = si->_used;
389 size_t alignment = os::vm_allocation_granularity();
390 size_t size = align_size_up(used, alignment);
391 char *requested_addr = si->_base;
393 // map the contents of the CDS archive in this memory
394 char *base = os::map_memory(_fd, _full_path, si->_file_offset,
395 requested_addr, size, si->_read_only,
396 si->_allow_exec);
397 if (base == NULL || base != si->_base) {
398 fail_continue(err_msg("Unable to map %s shared space at required address.", shared_region_name[i]));
399 return NULL;
400 }
401 #ifdef _WINDOWS
402 // This call is Windows-only because the memory_type gets recorded for the other platforms
403 // in method FileMapInfo::reserve_shared_memory(), which is not called on Windows.
404 MemTracker::record_virtual_memory_type((address)base, mtClassShared);
405 #endif
406 return base;
407 }
410 // Unmap a memory region in the address space.
412 void FileMapInfo::unmap_region(int i) {
413 struct FileMapInfo::FileMapHeader::space_info* si = &_header._space[i];
414 size_t used = si->_used;
415 size_t size = align_size_up(used, os::vm_allocation_granularity());
416 if (!os::unmap_memory(si->_base, size)) {
417 fail_stop("Unable to unmap shared space.");
418 }
419 }
422 void FileMapInfo::assert_mark(bool check) {
423 if (!check) {
424 fail_stop("Mark mismatch while restoring from shared file.", NULL);
425 }
426 }
429 FileMapInfo* FileMapInfo::_current_info = NULL;
432 // Open the shared archive file, read and validate the header
433 // information (version, boot classpath, etc.). If initialization
434 // fails, shared spaces are disabled and the file is closed. [See
435 // fail_continue.]
436 bool FileMapInfo::initialize() {
437 assert(UseSharedSpaces, "UseSharedSpaces expected.");
439 if (JvmtiExport::can_modify_any_class() || JvmtiExport::can_walk_any_space()) {
440 fail_continue("Tool agent requires sharing to be disabled.");
441 return false;
442 }
444 if (!open_for_read()) {
445 return false;
446 }
448 init_from_file(_fd);
449 if (!validate()) {
450 return false;
451 }
453 SharedReadOnlySize = _header._space[0]._capacity;
454 SharedReadWriteSize = _header._space[1]._capacity;
455 SharedMiscDataSize = _header._space[2]._capacity;
456 SharedMiscCodeSize = _header._space[3]._capacity;
457 return true;
458 }
461 bool FileMapInfo::validate() {
462 if (_header._version != current_version()) {
463 fail_continue("The shared archive file is the wrong version.");
464 return false;
465 }
466 if (_header._magic != (int)0xf00baba2) {
467 fail_continue("The shared archive file has a bad magic number.");
468 return false;
469 }
470 char header_version[JVM_IDENT_MAX];
471 get_header_version(header_version);
472 if (strncmp(_header._jvm_ident, header_version, JVM_IDENT_MAX-1) != 0) {
473 fail_continue("The shared archive file was created by a different"
474 " version or build of HotSpot.");
475 return false;
476 }
477 if (_header._obj_alignment != ObjectAlignmentInBytes) {
478 fail_continue("The shared archive file's ObjectAlignmentInBytes of %d"
479 " does not equal the current ObjectAlignmentInBytes of %d.",
480 _header._obj_alignment, ObjectAlignmentInBytes);
481 return false;
482 }
484 // Cannot verify interpreter yet, as it can only be created after the GC
485 // heap has been initialized.
487 if (_header._num_jars >= JVM_SHARED_JARS_MAX) {
488 fail_continue("Too many jar files to share.");
489 return false;
490 }
492 // Build checks on classpath and jar files
493 int num_jars_now = 0;
494 ClassPathEntry *cpe = ClassLoader::classpath_entry(0);
495 for ( ; cpe != NULL; cpe = cpe->next()) {
497 if (cpe->is_jar_file()) {
498 if (num_jars_now < _header._num_jars) {
500 // Jar file - verify timestamp and file size.
501 struct stat st;
502 const char *path = cpe->name();
503 if (os::stat(path, &st) != 0) {
504 fail_continue("Unable to open jar file %s.", path);
505 return false;
506 }
507 if (_header._jar[num_jars_now]._timestamp != st.st_mtime ||
508 _header._jar[num_jars_now]._filesize != st.st_size) {
509 fail_continue("A jar file is not the one used while building"
510 " the shared archive file.");
511 return false;
512 }
513 }
514 ++num_jars_now;
515 } else {
517 // If directories appear in boot classpath, they must be empty to
518 // avoid having to verify each individual class file.
519 const char* name = ((ClassPathDirEntry*)cpe)->name();
520 if (!os::dir_is_empty(name)) {
521 fail_continue("Boot classpath directory %s is not empty.", name);
522 return false;
523 }
524 }
525 }
526 if (num_jars_now < _header._num_jars) {
527 fail_continue("The number of jar files in the boot classpath is"
528 " less than the number the shared archive was created with.");
529 return false;
530 }
532 return true;
533 }
535 // The following method is provided to see whether a given pointer
536 // falls in the mapped shared space.
537 // Param:
538 // p, The given pointer
539 // Return:
540 // True if the p is within the mapped shared space, otherwise, false.
541 bool FileMapInfo::is_in_shared_space(const void* p) {
542 for (int i = 0; i < MetaspaceShared::n_regions; i++) {
543 if (p >= _header._space[i]._base &&
544 p < _header._space[i]._base + _header._space[i]._used) {
545 return true;
546 }
547 }
549 return false;
550 }