Add the memtrack utility.

This utility attempts to track the PSS usage of all of the
processes in the system. It will keep track of the min/max/avg/last
PSS for every process it has ever seen and dump that information when
the program is terminated or when a USR1 or TSTP signal is sent to
the process.

Change-Id: Id9364d5121b70f80b8335c379a241bee2fbdb019
diff --git a/memtrack/memtrack.h b/memtrack/memtrack.h
new file mode 100644
index 0000000..602fdb2
--- /dev/null
+++ b/memtrack/memtrack.h
@@ -0,0 +1,123 @@
+/*
+ * Copyright 2013 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 __MEMTRACK_H__
+#define __MEMTRACK_H__
+
+#include <sys/types.h>
+
+#include <map>
+#include <string>
+#include <vector>
+
+#define DEFAULT_SLEEP_DELAY_SECONDS 5
+#define NS_PER_SEC 1000000000LL
+
+class FileData {
+public:
+  FileData(char *filename, char *buffer, size_t buffer_len);
+  ~FileData();
+
+  // Get the PSS information from the file data. If there are no more
+  // PSS values to be found, return false.
+  bool getPss(size_t *pss);
+
+  // Check if there is at least bytes available in the file data.
+  bool isAvail(size_t bytes);
+
+private:
+  int fd_;
+  char *data_;
+  size_t max_;
+  size_t cur_idx_;
+  size_t len_;
+  bool read_complete_;
+};
+
+typedef struct {
+  std::string name;
+
+  size_t max_num_pids;
+
+  size_t num_samples;
+  double avg_pss_kb;
+  size_t min_pss_kb;
+  size_t max_pss_kb;
+  size_t last_pss_kb;
+
+  std::vector<int> pids;
+} process_info_t;
+typedef std::map<std::string, process_info_t> processes_t;
+
+typedef struct {
+  size_t pss_kb;
+
+  std::vector<int> pids;
+} cur_process_info_t;
+typedef std::map<std::string, cur_process_info_t> cur_processes_t;
+
+class ProcessInfo {
+public:
+  ProcessInfo();
+  ~ProcessInfo();
+
+  // Get the information about a single process.
+  bool getInformation(int pid, char *pid_str, size_t pid_str_len);
+
+  // Scan all of the running processes.
+  void scan();
+
+  // Dump the information about all of the processes in the system to the log.
+  void dumpToLog();
+
+private:
+  static const size_t kBufferLen = 4096;
+  static const size_t kCmdNameLen = 1024;
+
+  static const char *kProc;
+  static const size_t kProcLen = 6;
+
+  static const char *kCmdline;
+  static const size_t kCmdlineLen = 9;  // Includes \0 at end of string.
+
+  static const char *kSmaps;
+  static const size_t kSmapsLen = 7;  // Includes \0 at end of string.
+
+  static const char *kStatus;
+  static const size_t kStatusLen = 8;  // Includes \0 at end of string.
+
+  static const size_t kInitialEntries = 1000;
+
+  char proc_file_[PATH_MAX];
+  char buffer_[kBufferLen];
+
+  char cmd_name_[kCmdNameLen];
+
+  // Minimize a need for a lot of allocations by keeping our maps and
+  // lists in this object.
+  processes_t all_;
+  cur_processes_t cur_;
+  std::vector<const process_info_t *> list_;
+
+  // Compute a running average.
+  static inline void computeAvg(double *running_avg, size_t cur_avg,
+                                size_t num_samples) {
+    *running_avg = (*running_avg/(num_samples+1))*num_samples
+                   + (double)cur_avg/(num_samples+1);
+  }
+};
+
+#endif  // __MEMTRACK_H__