[Tarantool-patches] [PATCH 7/7] fiber: refactor C backtrace and add changelog
eelchinov at tarantool.org
eelchinov at tarantool.org
Thu Jul 1 18:54:50 MSK 2021
From: Egor Elchinov <eelchinov at tarantool.org>
Backtrace cache support and cxx demangling added.
DWARF version and lua test fixed
to support specific platforms.
Changelog added.
Closes: #4002
---
.../gh-4002-fiber-creation-backtrace.md | 8 +
src/lib/core/backtrace.cc | 164 +++++++++++++-----
.../gh-4002-fiber-creation-backtrace.result | 4 +-
.../gh-4002-fiber-creation-backtrace.test.lua | 4 +-
4 files changed, 132 insertions(+), 48 deletions(-)
create mode 100644 changelogs/unreleased/gh-4002-fiber-creation-backtrace.md
diff --git a/changelogs/unreleased/gh-4002-fiber-creation-backtrace.md b/changelogs/unreleased/gh-4002-fiber-creation-backtrace.md
new file mode 100644
index 000000000..1e1ac177a
--- /dev/null
+++ b/changelogs/unreleased/gh-4002-fiber-creation-backtrace.md
@@ -0,0 +1,8 @@
+## feature/fiber
+
+ * Added new subtable `parent_backtrace` to the `fiber.info()`
+ containing C and Lua backtrace chunks of fiber creation.
+ * Added `fiber.parent_bt_enable()` and `fiber.parent_bt_disable()`
+ options in order to switch on/off the ability to collect
+ parent backtraces for newly created fibers and to
+ show/hide `parent_backtrace` subtables in the `fiber.info()`.
diff --git a/src/lib/core/backtrace.cc b/src/lib/core/backtrace.cc
index f97c4c0a9..c82aa27af 100644
--- a/src/lib/core/backtrace.cc
+++ b/src/lib/core/backtrace.cc
@@ -47,7 +47,6 @@
#include <libunwind.h>
#ifdef TARGET_OS_DARWIN
-#include <execinfo.h>
#include <dlfcn.h>
#endif
@@ -79,19 +78,29 @@ backtrace_proc_cache_clear(void)
proc_cache = NULL;
}
-const char *
-get_proc_name(unw_cursor_t *unw_cur, unw_word_t *offset, bool skip_cache)
+int
+backtrace_proc_cache_find(unw_word_t ip, const char **name, unw_word_t *offset)
{
- static __thread char proc_name[BACKTRACE_NAME_MAX];
- unw_word_t ip;
- unw_get_reg(unw_cur, UNW_REG_IP, &ip);
+ struct proc_cache_entry *entry;
+ mh_int_t k;
- if (skip_cache) {
- unw_get_proc_name(unw_cur, proc_name, sizeof(proc_name),
- offset);
- return proc_name;
+ if (proc_cache != NULL) {
+ k = mh_i64ptr_find(proc_cache, ip, NULL);
+ if (k != mh_end(proc_cache)) {
+ entry = (struct proc_cache_entry *)
+ mh_i64ptr_node(proc_cache, k)->val;
+ *offset = entry->offset;
+ *name = entry->name;
+ return 0;
+ }
}
+ return -1;
+}
+
+int
+backtrace_proc_cache_put(unw_word_t ip, const char *name, unw_word_t offset)
+{
struct proc_cache_entry *entry;
struct mh_i64ptr_node_t node;
mh_int_t k;
@@ -99,39 +108,51 @@ get_proc_name(unw_cursor_t *unw_cur, unw_word_t *offset, bool skip_cache)
if (proc_cache == NULL) {
region_create(&cache_region, &cord()->slabc);
proc_cache = mh_i64ptr_new();
- if (proc_cache == NULL) {
- unw_get_proc_name(unw_cur, proc_name, sizeof(proc_name),
- offset);
- goto error;
- }
+ if (proc_cache == NULL)
+ return -1;
+ }
+
+ size_t size;
+ entry = region_alloc_object(&cache_region, typeof(*entry),
+ &size);
+ if (entry == NULL)
+ return -1;
+
+ node.key = ip;
+ node.val = entry;
+ entry->offset = offset;
+ snprintf(entry->name, BACKTRACE_NAME_MAX, "%s", name);
+
+ k = mh_i64ptr_put(proc_cache, &node, NULL, NULL);
+ if (k == mh_end(proc_cache)) {
+ size_t used = region_used(&cache_region);
+ region_truncate(&cache_region, used - size);
+ return -1;
}
- k = mh_i64ptr_find(proc_cache, ip, NULL);
- if (k != mh_end(proc_cache)) {
- entry = (struct proc_cache_entry *)
- mh_i64ptr_node(proc_cache, k)->val;
- snprintf(proc_name, BACKTRACE_NAME_MAX, "%s", entry->name);
- *offset = entry->offset;
- } else {
+ return 0;
+}
+
+const char *
+get_proc_name(unw_cursor_t *unw_cur, unw_word_t *offset, bool skip_cache)
+{
+ static __thread char proc_name[BACKTRACE_NAME_MAX];
+ const char *cache_name;
+ unw_word_t ip;
+
+ if (skip_cache) {
unw_get_proc_name(unw_cur, proc_name, sizeof(proc_name),
offset);
- size_t size;
- entry = region_alloc_object(&cache_region, typeof(*entry),
- &size);
- if (entry == NULL)
- goto error;
- node.key = ip;
- node.val = entry;
- snprintf(entry->name, BACKTRACE_NAME_MAX, "%s", proc_name);
- entry->offset = *offset;
-
- k = mh_i64ptr_put(proc_cache, &node, NULL, NULL);
- if (k == mh_end(proc_cache)) {
- free(entry);
- goto error;
- }
+ return proc_name;
}
-error:
+
+ unw_get_reg(unw_cur, UNW_REG_IP, &ip);
+ if (backtrace_proc_cache_find(ip, &cache_name, offset) == 0) {
+ return cache_name;
+ }
+
+ unw_get_proc_name(unw_cur, proc_name, sizeof(proc_name), offset);
+ backtrace_proc_cache_put(ip, proc_name, *offset);
return proc_name;
}
@@ -450,7 +471,25 @@ backtrace_collect_ip(void **ip_buf, int limit)
#ifndef TARGET_OS_DARWIN
unw_backtrace(ip_buf, limit);
#else
- backtrace(ip_buf, limit);
+ /*
+ * This dumb implementation was chosen because the DARWIN
+ * lacks unw_backtrace() routine from libunwind and
+ * usual backtrace() from <execinfo.h> has less capabilities
+ * than the libunwind version which uses DWARF.
+ */
+ unw_cursor_t unw_cur;
+ unw_context_t unw_ctx;
+ int frame_no = 0;
+ unw_word_t ip;
+
+ unw_getcontext(&unw_ctx);
+ unw_init_local(&unw_cur, &unw_ctx);
+
+ while (frame_no < limit && unw_step(&unw_cur) > 0) {
+ unw_get_reg(&unw_cur, UNW_REG_IP, &ip);
+ ip_buf[frame_no] = (void *)ip;
+ ++frame_no;
+ }
#endif
}
@@ -469,12 +508,15 @@ void
backtrace_foreach_ip(backtrace_cb cb, void **ip_buf, int limit,
void *cb_ctx)
{
+ int demangle_status;
+ char *demangle_buf = NULL;
+ size_t demangle_buf_len = 0;
#ifndef TARGET_OS_DARWIN
char proc_name[BACKTRACE_NAME_MAX];
unw_word_t ip = 0, offset = 0;
unw_proc_info_t pi;
int frame_no, ret = 0;
- char *proc = NULL;
+ const char *proc = NULL;
unw_accessors_t *acc = unw_get_accessors(unw_local_addr_space);
@@ -487,21 +529,37 @@ backtrace_foreach_ip(backtrace_cb cb, void **ip_buf, int limit,
frame_no++) {
ip = (unw_word_t)ip_buf[frame_no];
- if (acc->get_proc_name == NULL) {
+ if (backtrace_proc_cache_find(ip, &proc, &offset) == 0) {
+ ret = 0;
+ } else if (acc->get_proc_name == NULL) {
ret = unw_get_proc_info_by_ip(unw_local_addr_space,
ip, &pi, NULL);
offset = ip - pi.start_ip;
+ proc = NULL;
+ backtrace_proc_cache_put(ip, proc, offset);
} else {
ret = acc->get_proc_name(unw_local_addr_space, ip,
proc_name, sizeof(proc_name),
&offset, NULL);
proc = proc_name;
+ backtrace_proc_cache_put(ip, proc, offset);
+ }
+
+ if (proc != NULL) {
+ char *cxxname = abi::__cxa_demangle(proc, demangle_buf,
+ &demangle_buf_len,
+ &demangle_status);
+ if (cxxname != NULL) {
+ demangle_buf = cxxname;
+ proc = cxxname;
+ }
}
if (ret != 0 || cb(frame_no - 1, (void *)ip, proc,
(size_t)offset, cb_ctx) != 0)
break;
}
+ free(demangle_buf);
if (ret != 0)
say_debug("unwinding error: %s", unw_strerror(ret));
#else
@@ -509,17 +567,35 @@ backtrace_foreach_ip(backtrace_cb cb, void **ip_buf, int limit,
void *ip = NULL;
size_t offset = 0;
Dl_info dli;
+ const char *proc = NULL;
for (frame_no = 1; frame_no < limit && ip_buf[frame_no] != NULL;
++frame_no) {
ip = ip_buf[frame_no];
- ret = dladdr(ip, &dli);
- offset = (char *)ip - (char *)dli.dli_saddr;
+ if (backtrace_proc_cache_find((unw_word_t)ip, &proc,
+ &offset) == 0) {
+ ret = 0;
+ } else {
+ ret = dladdr(ip, &dli);
+ offset = (char *)ip - (char *)dli.dli_saddr;
+ proc = dli.dli_sname;
+ backtrace_proc_cache_put((unw_word_t)ip, proc, offset);
+ }
- if (cb(frame_no - 1, ip, dli.dli_sname, offset, cb_ctx) != 0)
+ if (proc != NULL) {
+ char *cxxname = abi::__cxa_demangle(proc, demangle_buf,
+ &demangle_buf_len,
+ &demangle_status);
+ if (cxxname != NULL) {
+ demangle_buf = cxxname;
+ proc = cxxname;
+ }
+ }
+ if (cb(frame_no - 1, ip, proc, offset, cb_ctx) != 0)
break;
}
+ free(demangle_buf);
if (ret == 0)
say_debug("unwinding error: %i", ret);
#endif
diff --git a/test/app/gh-4002-fiber-creation-backtrace.result b/test/app/gh-4002-fiber-creation-backtrace.result
index 6a075911d..91b0cb9ce 100644
--- a/test/app/gh-4002-fiber-creation-backtrace.result
+++ b/test/app/gh-4002-fiber-creation-backtrace.result
@@ -9,10 +9,10 @@ test_run = require('test_run').new()
| ---
| ...
-local stack_len = 0
+stack_len = 0
| ---
| ...
-local parent_stack_len = 0
+parent_stack_len = 0
| ---
| ...
diff --git a/test/app/gh-4002-fiber-creation-backtrace.test.lua b/test/app/gh-4002-fiber-creation-backtrace.test.lua
index 79a516860..3c39bb48e 100644
--- a/test/app/gh-4002-fiber-creation-backtrace.test.lua
+++ b/test/app/gh-4002-fiber-creation-backtrace.test.lua
@@ -2,8 +2,8 @@ yaml = require('yaml')
fiber = require('fiber')
test_run = require('test_run').new()
-local stack_len = 0
-local parent_stack_len = 0
+stack_len = 0
+parent_stack_len = 0
test_run:cmd('setopt delimiter ";"')
foo = function()
--
2.31.1
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