Implement malloc_info(3).

Expose jemalloc stats through the malloc_info(3) interface.

Bug: 16874689
Change-Id: I4358ac283002e60ff161107028d1a3fb1e9afb0a

5 files changed, 172 insertions, 0 deletions

diff --git a/libc/Android.mk b/libc/Android.mk
index 487cbd80e..6beb7b388 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -135,6 +135,7 @@ libc_bionic_src_files := \
     bionic/link.cpp \
     bionic/locale.cpp \
     bionic/lstat.cpp \
+    bionic/malloc_info.cpp \
     bionic/mbrtoc16.cpp \
     bionic/mbrtoc32.cpp \
     bionic/mbstate.cpp \
diff --git a/libc/bionic/dlmalloc.c b/libc/bionic/dlmalloc.c
index e89c5d1ff..fdb1b2642 100644
--- a/libc/bionic/dlmalloc.c
+++ b/libc/bionic/dlmalloc.c
@@ -16,6 +16,7 @@
 
 #include "dlmalloc.h"
 
+#include "malloc.h"
 #include "private/bionic_prctl.h"
 #include "private/libc_logging.h"
 
@@ -54,3 +55,25 @@ static void* named_anonymous_mmap(size_t length) {
   prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, map, length, "libc_malloc");
   return map;
 }
+
+// Since dlmalloc isn't the default, we'll leave this unimplemented for now. If
+// we decide we need it later, we can fill it in.
+size_t __mallinfo_narenas() {
+  return 0;
+}
+
+size_t __mallinfo_nbins() {
+  return 0;
+}
+
+struct mallinfo __mallinfo_arena_info(size_t) {
+  struct mallinfo mi;
+  memset(&mi, 0, sizeof(mi));
+  return mi;
+}
+
+struct mallinfo __mallinfo_bin_info(size_t, size_t) {
+  struct mallinfo mi;
+  memset(&mi, 0, sizeof(mi));
+  return mi;
+}
diff --git a/libc/bionic/malloc_info.cpp b/libc/bionic/malloc_info.cpp
new file mode 100644
index 000000000..99caedbad
--- /dev/null
+++ b/libc/bionic/malloc_info.cpp
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "malloc_info.h"
+
+#include <errno.h>
+#include "private/bionic_macros.h"
+
+class __LIBC_HIDDEN__ Elem {
+public:
+  // name must be valid throughout lifetime of the object.
+  explicit Elem(FILE* fp, const char* name,
+                const char* attr_fmt = nullptr, ...) {
+    this->fp = fp;
+    this->name = name;
+
+    fprintf(fp, "<%s", name);
+    if (attr_fmt != nullptr) {
+      va_list args;
+      va_start(args, attr_fmt);
+      fputc(' ', fp);
+      vfprintf(fp, attr_fmt, args);
+      va_end(args);
+    }
+    fputc('>', fp);
+  }
+
+  ~Elem() noexcept {
+    fprintf(fp, "</%s>", name);
+  }
+
+  void contents(const char* fmt, ...) {
+      va_list args;
+      va_start(args, fmt);
+      vfprintf(fp, fmt, args);
+      va_end(args);
+  }
+
+private:
+  FILE* fp;
+  const char* name;
+
+  DISALLOW_COPY_AND_ASSIGN(Elem);
+};
+
+int malloc_info(int options, FILE* fp) {
+  if (options != 0) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  Elem root(fp, "malloc", "version=\"jemalloc-1\"");
+
+  // Dump all of the large allocations in the arenas.
+  for (size_t i = 0; i < __mallinfo_narenas(); i++) {
+    struct mallinfo mi = __mallinfo_arena_info(i);
+    if (mi.hblkhd != 0) {
+      Elem arena_elem(fp, "heap", "nr=\"%d\"", i);
+      {
+        Elem(fp, "allocated-large").contents("%zu", mi.ordblks);
+        Elem(fp, "allocated-huge").contents("%zu", mi.uordblks);
+        Elem(fp, "allocated-bins").contents("%zu", mi.fsmblks);
+
+        size_t total = 0;
+        for (size_t j = 0; j < __mallinfo_nbins(); j++) {
+          struct mallinfo mi = __mallinfo_bin_info(i, j);
+          if (mi.ordblks != 0) {
+            Elem bin_elem(fp, "bin", "nr=\"%d\"", j);
+            Elem(fp, "allocated").contents("%zu", mi.ordblks);
+            Elem(fp, "nmalloc").contents("%zu", mi.uordblks);
+            Elem(fp, "ndalloc").contents("%zu", mi.fordblks);
+            total += mi.ordblks;
+          }
+        }
+        Elem(fp, "bins-total").contents("%zu", total);
+      }
+    }
+  }
+
+  return 0;
+}
diff --git a/libc/bionic/malloc_info.h b/libc/bionic/malloc_info.h
new file mode 100644
index 000000000..5fffae980
--- /dev/null
+++ b/libc/bionic/malloc_info.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef LIBC_BIONIC_MALLOC_INFO_H_
+#define LIBC_BIONIC_MALLOC_INFO_H_
+
+#include <malloc.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+__LIBC_HIDDEN__ size_t __mallinfo_narenas();
+__LIBC_HIDDEN__ size_t __mallinfo_nbins();
+__LIBC_HIDDEN__ struct mallinfo __mallinfo_arena_info(size_t);
+__LIBC_HIDDEN__ struct mallinfo __mallinfo_bin_info(size_t, size_t);
+
+__END_DECLS
+
+#endif // LIBC_BIONIC_MALLOC_INFO_H_
diff --git a/libc/include/malloc.h b/libc/include/malloc.h
index e6ea27606..cb1dd3bcf 100644
--- a/libc/include/malloc.h
+++ b/libc/include/malloc.h
@@ -24,6 +24,7 @@
  */
 #include <sys/cdefs.h>
 #include <stddef.h>
+#include <stdio.h>
 
 __BEGIN_DECLS
 
@@ -53,6 +54,27 @@ struct mallinfo {
 
 extern struct mallinfo mallinfo(void);
 
+/*
+ * XML structure for malloc_info(3) is in the following format:
+ *
+ * <malloc version="jemalloc-1">
+ *   <heap nr="INT">
+ *     <allocated-large>INT</allocated-large>
+ *     <allocated-huge>INT</allocated-huge>
+ *     <allocated-bins>INT</allocated-bins>
+ *     <bins-total>INT</bins-total>
+ *     <bin nr="INT">
+ *       <allocated>INT</allocated>
+ *       <nmalloc>INT</nmalloc>
+ *       <ndalloc>INT</ndalloc>
+ *     </bin>
+ *     <!-- more bins -->
+ *   </heap>
+ *   <!-- more heaps -->
+ * </malloc>
+ */
+extern int malloc_info(int, FILE *);
+
 __END_DECLS
 
 #endif  /* LIBC_INCLUDE_MALLOC_H_ */