stats: rename to sys-stats + refactor

Make stats module handle only system-wide statistics.

Change-Id: If9b391e7a635ec3185a3459a25ed49c758721f98

10 files changed, 272 insertions, 374 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 422cfed..dfbd9e3 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -26,7 +26,7 @@ SET(SRCS
 	config-deserializer.c
 	appinfo-provider.c
 	report-json-serializer.c
-	stats.c
+	sys-stats.c
 	clock.c
 	ipc.c
 	process.c
diff --git a/src/proc-scanner.c b/src/proc-scanner.c
index b2fdf9e..336a23f 100644
--- a/src/proc-scanner.c
+++ b/src/proc-scanner.c
@@ -140,7 +140,7 @@ static bool _proc_scanner_read_pid(int pid, void *user_data)
 	struct process *proc = _proc_scanner_find_process_in_history(scanner, pid);
 
 	if (!proc) {
-		process_init(pid, &proc_new);
+		process_init_process(pid, &proc_new);
 		proc = &proc_new;
 	}
 
diff --git a/src/process.c b/src/process.c
index 70f4bb0..17159f7 100644
--- a/src/process.c
+++ b/src/process.c
@@ -1,11 +1,18 @@
 #include <string.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 #include "process.h"
+#include "clock.h"
+#include "sys-stats.h"
 #include "err-check.h"
 #include "procfs.h"
 #include "appinfo-provider.h"
 
+static struct sys_stats sys;
+static int pagesize;
+static float timescale;
+
 int process_get_memory_usage(struct process *proc, int *usage)
 {
 	ON_NULL_RETURN_VAL(proc, -1);
@@ -35,12 +42,15 @@ int process_update(struct process *proc)
 	ticks = info.stime + info.utime;
 	proc->frame_ticks_used = ticks - proc->total_ticks_used;
 	proc->total_ticks_used = ticks;
-	proc->memory_used = info.rss * stats_get_page_size() / 1024;
+	proc->memory_used = info.rss * pagesize / 1024;
+	float now = clock_monotonic_get();
+	proc->frame_time_inverted = 1.0f / (now - proc->update_time);
+	proc->update_time = now;
 
 	return 0;
 }
 
-void process_init(int pid, struct process *proc)
+void process_init_process(int pid, struct process *proc)
 {
 	memset(proc, 0x0, sizeof(struct process));
 	proc->pid = pid;
@@ -87,3 +97,32 @@ void process_move(struct process *dst, struct process *src)
 	src->appid = NULL;
 	src->exe = NULL;
 }
+
+int process_get_cpu_usage_percentage(struct process *proc, float *usage)
+{
+	ON_NULL_RETURN_VAL(proc, -1);
+	ON_NULL_RETURN_VAL(usage, -1);
+
+	*usage = (float)proc->frame_ticks_used * proc->frame_time_inverted * timescale;
+	return 0;
+}
+
+int process_get_memory_usage_percentage(struct process *proc, float *usage)
+{
+	ON_NULL_RETURN_VAL(proc, -1);
+	ON_NULL_RETURN_VAL(usage, -1);
+
+	*usage = (float)proc->memory_used / sys.total_memory;
+	return 0;
+}
+
+int process_init()
+{
+	if (sys_stats_update(&sys) != 0) {
+		ERR("stats_update_system_stats failed.");
+		return -1;
+	}
+	timescale = 1.0f / (float)sysconf(_SC_CLK_TCK);
+	pagesize = getpagesize();
+	return 0;
+}
diff --git a/src/process.h b/src/process.h
index 7d13938..12344ee 100644
--- a/src/process.h
+++ b/src/process.h
@@ -17,10 +17,6 @@
 #ifndef __PROCESS_H
 #define __PROCESS_H
 
-#include <stdbool.h>
-
-#include "stats.h"
-
 /**
  * @brief The process structure.
  *
@@ -35,9 +31,16 @@ struct process
 	unsigned long long total_ticks_used;
 	unsigned long long frame_ticks_used;
 	int memory_used;
+	float update_time;
+	float frame_time_inverted;
 };
 
 /**
+ * @brief Initialize process module.
+ */
+int process_init();
+
+/**
  * @brief Gets last read process memory usage
  *
  * @param[in]: proc process
@@ -74,7 +77,7 @@ int process_update(struct process *proc);
  *
  * @return 0 on success, other value on error.
  */
-void process_init(int pid, struct process *proc);
+void process_init_process(int pid, struct process *proc);
 
 /**
  * @brief Shutdown process structure
@@ -122,4 +125,24 @@ const char *process_get_exe(struct process *proc);
  */
 void process_move(struct process *dst, struct process *src);
 
+/**
+ * @brief Gets average CPU usage percentage since last update.
+ *
+ * @param[in]: proc process
+ * @param[out]: usage the cpu usage percentage
+ *
+ * @return 0 on success, other value on error.
+ */
+int process_get_cpu_usage_percentage(struct process *proc, float *usage);
+
+/**
+ * @brief Gets average memory usage percentage on last update.
+ *
+ * @param[in]: proc process
+ * @param[out]: usage the memory usage percentage
+ *
+ * @return 0 on success, other value on error.
+ */
+int process_get_memory_usage_percentage(struct process *dst, float *usage);
+
 #endif
diff --git a/src/report-generator.c b/src/report-generator.c
index 3901899..c6e761f 100644
--- a/src/report-generator.c
+++ b/src/report-generator.c
@@ -24,21 +24,24 @@
 #include "log.h"
 #include "err-check.h"
 #include "appinfo-provider.h"
-#include "stats.h"
+#include "sys-stats.h"
 #include "clock.h"
 #include "proc-scanner.h"
+#include "process.h"
 
 struct report_generator_system {
 	/** system cpu usage statistics */
-	struct stats_system previous;
+	struct sys_stats stats;
 };
 
 struct report_generator_process
 {
 	/** process pid */
 	int pid;
-	/** process cpu usage statistics */
-	struct stats_process previous;
+	/** process statistics */
+	struct process proc;
+	/** update time */
+	float proc_update_time;
 };
 
 struct report_generator_app
@@ -49,14 +52,14 @@ struct report_generator_app
 
 struct report_generator_top
 {
-	struct stats_system sys_stats;
+	struct sys_stats sys_stats;
 	proc_scanner_t *scanner;
 	report_generator_top_type_e type;
 	int limit;
 };
 
 struct report_generator_top_closure {
-	struct stats_system sys_stats;
+	struct sys_stats sys_stats;
 	int current_index;
 	int max_index;
 	struct process_usage_report *usage_report;
@@ -71,7 +74,7 @@ report_generator_system_t *report_generator_new_system_report_generator()
 	if (!ret)
 		return NULL;
 
-	if (stats_update_system_stats(&ret->previous) != 0) {
+	if (sys_stats_update(&ret->stats) != 0) {
 		ERR("stats_update_system_stats failed");
 		free(ret);
 		return NULL;
@@ -96,12 +99,15 @@ report_generator_process_t *report_generator_new_process_report_generator(int pi
 	if (!ret)
 		return NULL;
 
-	if (stats_update_process_stats(pid, &ret->previous) != 0) {
-		ERR("stats_update_process_stats failed.");
+	process_init(pid, &ret->proc);
+
+	if (process_update(&ret->proc) != 0) {
+		ERR("process_update failed.");
 		free(ret);
 		return NULL;
 	};
 
+	ret->proc_update_time = clock_monotonic_get();
 	ret->pid = pid;
 
 	return ret;
@@ -146,14 +152,13 @@ int report_generator_generate_system_cpu_usage_report(
 	ON_NULL_RETURN_VAL(report, -1);
 
 	float usage;
-	struct stats_system current;
 
-	if (stats_update_system_stats(&current) != 0) {
+	if (sys_stats_update(&generator->stats) != 0) {
 		ERR("stats_update_system_stats failed.");
 		return -1;
 	}
 
-	if (stats_get_system_cpu_usage_average(&generator->previous, &current, &usage))
+	if (sys_stats_get_cpu_usage_percentage(&generator->stats, &usage))
 	{
 		ERR("stats_get_system_cpu_usage_average failed");
 		return -1;
@@ -162,8 +167,6 @@ int report_generator_generate_system_cpu_usage_report(
 	report->usage = usage;
 	report->time = clock_realtime_get();
 
-	generator->previous = current;
-
 	return 0;
 }
 
@@ -175,12 +178,12 @@ int report_generator_generate_system_memory_usage_report(
 
 	float usage;
 
-	if (stats_update_system_stats(&generator->previous) != 0) {
+	if (sys_stats_update(&generator->stats) != 0) {
 		ERR("stats_update_system_stats failed.");
 		return -1;
 	}
 
-	if (stats_get_system_memory_usage(&generator->previous, &usage) != 0) {
+	if (sys_stats_get_memory_usage_percentage(&generator->stats, &usage) != 0) {
 		ERR("stats_get_system_memory_usage failed.");
 		return -1;
 	}
@@ -198,16 +201,15 @@ int report_generator_generate_process_cpu_usage_report(
 	ON_NULL_RETURN_VAL(generator, -1);
 	ON_NULL_RETURN_VAL(report, -1);
 
-	struct stats_process current = {0,};
 	float usage;
 
-	if (stats_update_process_stats(generator->pid, &current) != 0) {
-		ERR("stats_update_process_stats failed.");
+	if (process_update(&generator->proc) != 0) {
+		ERR("process_update failed.");
 		return -1;
 	}
 
-	if (stats_get_process_cpu_usage_average(&generator->previous, &current, &usage) ) {
-		ERR("stats_update_process_stats failed.");
+	if (process_get_cpu_usage_percentage(&generator->proc, &usage) != 0) {
+		ERR("process_get_cpu_usage_percentage failed.");
 		return -1;
 	}
 
@@ -215,8 +217,6 @@ int report_generator_generate_process_cpu_usage_report(
 	report->pid = generator->pid;
 	report->usage = usage;
 
-	generator->previous = current;
-
 	return 0;
 }
 
@@ -229,8 +229,8 @@ int report_generator_generate_process_memory_usage_report(
 
 	float usage;
 
-	if (stats_get_process_memory_usage(generator->pid, &usage) != 0) {
-		ERR("stats_get_process_memory_usage failed.");
+	if (process_get_memory_usage_percentage(&generator->proc, &usage) != 0) {
+		ERR("process_get_memory_usage_percentage failed.");
 		return -1;
 	}
 
@@ -311,7 +311,7 @@ int report_generator_generate_load_average_report(struct system_load_average_rep
 
 	float a1, a5, a15;
 
-	if (stats_get_load_averages(&a1, &a5, &a15) != 0) {
+	if (sys_stats_get_load_averages(&a1, &a5, &a15) != 0) {
 		ERR("stats_get_load_averages failed.");
 		return -1;
 	}
@@ -344,7 +344,7 @@ report_generator_top_t *report_generator_new_top_report_generator(report_generat
 		report_generator_free_top_generator(gen);
 		return NULL;
 	}
-	if (stats_update_system_stats(&gen->sys_stats) != 0) {
+	if (sys_stats_update(&gen->sys_stats) != 0) {
 		report_generator_free_top_generator(gen);
 		return NULL;
 	}
@@ -389,15 +389,12 @@ static bool _append_to_cpu_report(struct process *proc, void *data)
 	struct report_generator_top_closure *closure = data;
 	struct process_usage_report report = {0,};
 	const char *appid;
-	unsigned long long ticks = 0;
 
 	if (closure->current_index >= closure->max_index)
 		return false;
 
-	if (process_get_cpu_usage(proc, &ticks) != 0) {
+	if (process_get_cpu_usage_percentage(proc, &report.usage) != 0) {
 		report.usage = NAN;
-	} else {
-		report.usage = stats_get_cpu_usage_percentage(ticks, closure->sys_stats.frame_time_inverted);
 	}
 
 	appid = process_get_appid(proc);
@@ -498,7 +495,7 @@ int report_generator_generate_top_cpu_report(
 
 	struct report_generator_top_closure closure = {0,};
 
-	if (stats_update_system_stats(&generator->sys_stats) != 0) {
+	if (sys_stats_update(&generator->sys_stats) != 0) {
 		return -1;
 	}
 
@@ -539,7 +536,7 @@ int report_generator_generate_top_memory_report(
 
 	struct report_generator_top_closure closure = {0,};
 
-	if (stats_update_system_stats(&generator->sys_stats) != 0) {
+	if (sys_stats_update(&generator->sys_stats) != 0) {
 		return -1;
 	}
 
diff --git a/src/stats.c b/src/stats.c
deleted file mode 100644
index ef22b1b..0000000
--- a/src/stats.c
+++ /dev/null
@@ -1,177 +0,0 @@
-/*
- * Copyright (c) 2018 Samsung Electronics Co., Ltd.
- *
- * Licensed under the Flora License, Version 1.1 (the License);
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://floralicense.org/license/
- *
- * 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 <unistd.h>
-
-#include "stats.h"
-#include "procfs.h"
-#include "err-check.h"
-#include "clock.h"
-
-static int ncpus;
-static float timescale;
-
-int stats_get_system_cpu_usage_average(struct stats_system *previous, struct stats_system *current, float *usage)
-{
-	struct stats_system diff;
-
-	diff.busy_ticks = current->busy_ticks > previous->busy_ticks ? current->busy_ticks - previous->busy_ticks : 0;
-
-	diff.total_ticks = current->total_ticks > previous->total_ticks ? current->total_ticks - previous->total_ticks : 0;
-
-	if (diff.total_ticks == 0) {
-		*usage = 0;
-	} else {
-		*usage = (float)diff.busy_ticks / diff.total_ticks;
-	}
-
-	return 0;
-}
-
-int stats_update_system_stats(struct stats_system *sys)
-{
-	ON_NULL_RETURN_VAL(sys, -1);
-
-	struct procfs_stat cpu_info;
-	struct procfs_meminfo mem_info;
-
-	if (procfs_read_stat(&cpu_info) != 0) {
-		return -1;
-	}
-
-	if (procfs_read_meminfo(&mem_info) != 0) {
-		ERR("procfs_read_meminfo failed.");
-		return -1;
-	}
-
-	sys->busy_ticks = cpu_info.user + cpu_info.system + cpu_info.nice + cpu_info.irq + cpu_info.softirq;
-	sys->total_ticks = cpu_info.user + cpu_info.system + cpu_info.nice + cpu_info.irq + cpu_info.softirq + cpu_info.idle + cpu_info.iowait;
-	sys->memory_used = mem_info.used;
-	sys->total_memory = mem_info.total;
-
-	float now = clock_monotonic_get();
-	sys->frame_time_inverted = 1.0f / (now - sys->update_time);
-	sys->update_time = now;
-
-	return 0;
-}
-
-int stats_get_system_memory_usage(struct stats_system *sys, float *usage)
-{
-	ON_NULL_RETURN_VAL(usage, -1);
-
-	*usage = (float)sys->memory_used / sys->total_memory;
-
-	return 0;
-}
-
-int stats_update_process_stats(int pid, struct stats_process *stats)
-{
-	ON_TRUE_RETURN_VAL(pid < 0, -1);
-	ON_NULL_RETURN_VAL(stats, -1);
-
-	struct procfs_process_stat proc_info;
-	struct procfs_stat sys_info;
-
-	if (procfs_read_process_stat(pid, &proc_info) != 0) {
-		ERR("procfs_read_process_stat failed.");
-		return -1;
-	}
-
-	if (procfs_read_stat(&sys_info) != 0) {
-		ERR("procfs_read_stat failed.");
-		return -1;
-	}
-
-	stats->process_ticks = proc_info.stime + proc_info.utime;
-	stats->system_ticks = sys_info.user + sys_info.system + sys_info.nice + sys_info.idle;
-
-	return 0;
-}
-
-int stats_get_process_cpu_usage_average(struct stats_process *previous, struct stats_process *current, float *usage)
-{
-	struct stats_process diff;
-
-	diff.process_ticks = current->process_ticks > previous->process_ticks ? current->process_ticks - previous->process_ticks: 0;
-	diff.system_ticks = current->system_ticks > previous->system_ticks ? current->system_ticks - previous->system_ticks : 0;
-
-	if (diff.system_ticks == 0)
-		*usage = 0;
-	else
-		*usage = (float)diff.process_ticks / diff.system_ticks * ncpus;
-
-	return 0;
-}
-
-int stats_get_process_memory_usage(int pid, float *usage)
-{
-	ON_TRUE_RETURN_VAL(pid < 0, -1);
-	ON_NULL_RETURN_VAL(usage, -1);
-
-	struct procfs_process_smaps mem_info;
-	struct procfs_meminfo sys_meminfo;
-
-	if (procfs_read_process_smaps(pid, &mem_info) != 0) {
-		ERR("procfs_read_process_smaps failed.");
-		return -1;
-	}
-
-	if (procfs_read_meminfo(&sys_meminfo) != 0) {
-		ERR("procfs_read_meminfo failed.");
-		return -1;
-	}
-
-	*usage = sys_meminfo.total > 0 ? (float)mem_info.rss / sys_meminfo.total : 0;
-
-	return 0;
-}
-
-int stats_get_load_averages(float *a1, float *a5, float *a15)
-{
-	struct procfs_loadavg info;
-
-	if (procfs_read_loadavg(&info) != 0) {
-		ERR("procfs_read_loadavg failed.");
-		return -1;
-	}
-
-	if (a1) *a1 = info.one_min_avg;
-	if (a5) *a5 = info.five_min_avg;
-	if (a15) *a15 = info.fifteen_min_avg;
-
-	return 0;
-}
-
-float stats_get_cpu_usage_percentage(unsigned long long ticks_delta, float ticks_time_inverted)
-{
-	return (float)ticks_delta * ticks_time_inverted * timescale;
-}
-
-int stats_init()
-{
-	if (procfs_read_cpu_possible(&ncpus) != 0) {
-		ERR("procfs_read_cpu_possible failed.");
-		return -1;
-	}
-	timescale = 1.0f / (float)sysconf(_SC_CLK_TCK);
-	return 0;
-}
-
-int stats_get_page_size()
-{
-	return getpagesize();
-}
diff --git a/src/stats.h b/src/stats.h
deleted file mode 100644
index 5ee9956..0000000
--- a/src/stats.h
+++ /dev/null
@@ -1,151 +0,0 @@
-/*
- * Copyright (c) 2018 Samsung Electronics Co., Ltd.
- *
- * Licensed under the Flora License, Version 1.1 (the License);
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://floralicense.org/license/
- *
- * 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 _STATS_H_
-#define _STATS_H_
-
-#include <time.h>
-
-/**
- * @brief System's statistics snapshot
- */
-struct stats_system
-{
-	unsigned long long busy_ticks;
-	unsigned long long total_ticks;
-	unsigned long long memory_used;
-	unsigned long long total_memory;
-	float update_time;
-	float frame_time_inverted;
-};
-
-/**
- * @brief Process's statistics snapshot
- */
-struct stats_process
-{
-	unsigned long long system_ticks;
-	unsigned long long process_ticks;
-};
-
-/**
- * @brief Initializes stats module.
- *
- * @return: 0 on success, other value on error.
- *
- * @note function should be called before any other function call from this
- * module.
- */
-int stats_init();
-
-/**
- * @brief Calculates average cpu usage between two stats snapshots.
- *
- * @param[in] previous the stats snapshots taken before current
- * @param[in] current the stats snapshots taken after previous
- * @param[out] usage the cpu usage as percent.
- *
- * @return: 0 on success, other value on error
- */
-int stats_get_system_cpu_usage_average(struct stats_system *previous, struct stats_system *current, float *usage);
-
-/**
- * @brief Takes system statistics snapshot.
- *
- * @param[out] stats System's statistics snapshot.
- *
- * @return: 0 on success, other value on error
- */
-int stats_update_system_stats(struct stats_system *stats);
-
-/**
- * @brief Calculates system memory usage.
- *
- * @param[out] usage the memory usage as percent.
- *
- * @return: 0 on success, other value on error
- */
-int stats_get_system_memory_usage(struct stats_system *stats, float *usage);
-
-/**
- * @brief Takes process statistics snapshot.
- *
- * @param[in] pid the process id.
- * @param[out] stats process statistcs.
- *
- * @return: 0 on success, other value on error
- */
-int stats_update_process_stats(int pid, struct stats_process *stats);
-
-/**
- * @brief Calculates average process cpu usage between two stats snapshots.
- *
- * @param[in] previous the stats snapshots taken before current
- * @param[in] current the stats snapshots taken after previous
- * @param[out] usage the cpu usage as percent. It may be greater then 100% in
- * case of multithreaded applications.
- *
- * @note in case when process has 2 threads which runs tight loop, the function
- * will report 200% usage.
- *
- * @return: 0 on success, other value on error
- */
-int stats_get_process_cpu_usage_average(struct stats_process *previous, struct stats_process *current, float *usage);
-
-/**
- * @brief Calculates process memory usage.
- *
- * @param[in] pid the process id.
- * @param[out] usage process memory usage.
- *
- * @return: 0 on success, other value on error
- */
-int stats_get_process_memory_usage(int pid, float *usage);
-
-/**
- * @brief Gets system load averages stats.
- *
- * @param[out] a1 one minute average.
- * @param[out] a5 five minute average.
- * @param[out] a15 fifteen minute average.
- *
- * @return: 0 on success, other value on error
- */
-int stats_get_load_averages(float *a1, float *a5, float *a15);
-
-/**
- * @brief Gets CPU usage percentage
- *
- * @param[in] ticks_delta the amount of clock ticks
- * @param[in] ticks_time_inverted the time of ticks_delete inverted ^-1
- *
- * @return: CPU usage perecentage
- *
- * @note in case when process has 2 threads which runs tight loop, the function
- * will report 200% usage (2.0f).
- */
-float stats_get_cpu_usage_percentage(unsigned long long ticks_delta, float ticks_time_inverted);
-
-/**
- * @brief Get system's page size in bytes.
- *
- * @return page size
- */
-int stats_get_page_size();
-
-#endif
-
-
diff --git a/src/sys-stats.c b/src/sys-stats.c
new file mode 100644
index 0000000..bcd3812
--- /dev/null
+++ b/src/sys-stats.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2018 Samsung Electronics Co., Ltd.
+ *
+ * Licensed under the Flora License, Version 1.1 (the License);
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://floralicense.org/license/
+ *
+ * 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 <unistd.h>
+
+#include "sys-stats.h"
+#include "procfs.h"
+#include "err-check.h"
+#include "clock.h"
+
+int sys_stats_get_cpu_usage_percentage(struct sys_stats *stats, float *usage)
+{
+	ON_NULL_RETURN_VAL(stats, -1);
+	ON_NULL_RETURN_VAL(usage, -1);
+
+	if (stats->total_ticks_delta == 0) {
+		*usage = 0;
+	} else {
+		*usage = (float)stats->busy_ticks_delta / stats->total_ticks_delta;
+	}
+
+	return 0;
+}
+
+int sys_stats_update(struct sys_stats *sys)
+{
+	ON_NULL_RETURN_VAL(sys, -1);
+
+	struct procfs_stat cpu_info;
+	struct procfs_meminfo mem_info;
+	unsigned long long ticks;
+
+	if (procfs_read_stat(&cpu_info) != 0) {
+		ERR("procfs_read_stat failed.");
+		return -1;
+	}
+
+	if (procfs_read_meminfo(&mem_info) != 0) {
+		ERR("procfs_read_meminfo failed.");
+		return -1;
+	}
+
+	ticks = cpu_info.user + cpu_info.system + cpu_info.nice + cpu_info.irq + cpu_info.softirq;
+	sys->busy_ticks_delta = ticks > sys->busy_ticks ? ticks - sys->busy_ticks : 0;
+	sys->busy_ticks = ticks;
+
+	ticks = cpu_info.user + cpu_info.system + cpu_info.nice + cpu_info.irq +
+		cpu_info.softirq + cpu_info.idle + cpu_info.iowait;
+	sys->total_ticks_delta = ticks > sys->total_ticks ? ticks - sys->total_ticks : 0;
+	sys->total_ticks = ticks;
+
+	sys->memory_used = mem_info.used;
+	sys->total_memory = mem_info.total;
+
+	return 0;
+}
+
+int sys_stats_get_memory_usage_percentage(struct sys_stats *sys, float *usage)
+{
+	ON_NULL_RETURN_VAL(sys, -1);
+	ON_NULL_RETURN_VAL(usage, -1);
+
+	*usage = (float)sys->memory_used / sys->total_memory;
+
+	return 0;
+}
+
+int sys_stats_get_load_averages(float *a1, float *a5, float *a15)
+{
+	struct procfs_loadavg info;
+
+	if (procfs_read_loadavg(&info) != 0) {
+		ERR("procfs_read_loadavg failed.");
+		return -1;
+	}
+
+	if (a1) *a1 = info.one_min_avg;
+	if (a5) *a5 = info.five_min_avg;
+	if (a15) *a15 = info.fifteen_min_avg;
+
+	return 0;
+}
diff --git a/src/sys-stats.h b/src/sys-stats.h
new file mode 100644
index 0000000..8c2d784
--- /dev/null
+++ b/src/sys-stats.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2018 Samsung Electronics Co., Ltd.
+ *
+ * Licensed under the Flora License, Version 1.1 (the License);
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://floralicense.org/license/
+ *
+ * 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 _SYS_STATS_H_
+#define _SYS_STATS_H_
+
+/**
+ * @brief System's statistics snapshot
+ */
+struct sys_stats
+{
+	unsigned long long busy_ticks;
+	unsigned long long busy_ticks_delta;
+	unsigned long long total_ticks;
+	unsigned long long total_ticks_delta;
+	unsigned long long memory_used;
+	unsigned long long total_memory;
+};
+
+/**
+ * @brief Calculates average cpu usage between two stats snapshots.
+ *
+ * @param[in] stats the stats snapshots
+ * @param[out] usage the cpu usage as percent.
+ *
+ * @return: 0 on success, other value on error
+ */
+int sys_stats_get_cpu_usage_percentage(struct sys_stats *stats, float *usage);
+
+/**
+ * @brief Takes system statistics snapshot.
+ *
+ * @param[out] stats System's statistics snapshot.
+ *
+ * @return: 0 on success, other value on error
+ */
+int sys_stats_update(struct sys_stats *stats);
+
+/**
+ * @brief Calculates system memory usage.
+ *
+ * @param[out] usage the memory usage as percent.
+ *
+ * @return: 0 on success, other value on error
+ */
+int sys_stats_get_memory_usage_percentage(struct sys_stats *stats, float *usage);
+
+/**
+ * @brief Gets system load averages stats.
+ *
+ * @param[out] a1 one minute average.
+ * @param[out] a5 five minute average.
+ * @param[out] a15 fifteen minute average.
+ *
+ * @return: 0 on success, other value on error
+ */
+int sys_stats_get_load_averages(float *a1, float *a5, float *a15);
+
+#endif
diff --git a/src/task-worker.c b/src/task-worker.c
index 37caf1e..6f6a9d3 100644
--- a/src/task-worker.c
+++ b/src/task-worker.c
@@ -24,7 +24,7 @@
 #include "log.h"
 #include "scheduler.h"
 #include "task-worker.h"
-#include "stats.h"
+#include "process.h"
 #include "ipc.h"
 
 static gboolean sigint_handler(gpointer user_data);
@@ -59,9 +59,9 @@ int main(int argc, char *argv[])
 
 	app_provider_init();
 	ipc_init(argv[1], task_counter);
-	if (stats_init() != 0)
+	if (process_init() != 0)
 	{
-		ERR("Stats module initialization failed");
+		ERR("Process module initialization failed");
 		g_free(data.current_config);
 		ipc_shutdown();
 		app_provider_shutdown();
@@ -95,4 +95,4 @@ static gboolean sigint_handler(gpointer user_data)
 	g_main_loop_quit(data.main_loop);
 
 	return TRUE;
-}
\ No newline at end of file
+}