Process memory measurement

[dabonnie]

Added functionality to measure the process memory (percentage used) by extending a PeriodicMeasurementNode. See https://github.com/ros-security/aws-roadmap/issues/139 for details.

[dabonnie]

Example output from running the main (with the system cpu and memory nodes inactive):

[DEBUG] [1575679186.636252688] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002228
[DEBUG] [1575679186.636802710] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002228, min=0.002228, max=0.002228, std_dev=0.000000, count=1
[DEBUG] [1575679187.637456631] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002326
[DEBUG] [1575679187.637536597] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002277, min=0.002228, max=0.002326, std_dev=0.000049, count=2
[DEBUG] [1575679188.653486770] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679188.653563781] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002391, min=0.002228, max=0.002620, std_dev=0.000167, count=3
[DEBUG] [1575679189.641113199] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679189.641340374] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002449, min=0.002228, max=0.002620, std_dev=0.000175, count=4
[DEBUG] [1575679190.697711072] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679190.697782464] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002483, min=0.002228, max=0.002620, std_dev=0.000171, count=5
[DEBUG] [1575679191.645000999] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679191.645067954] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002506, min=0.002228, max=0.002620, std_dev=0.000164, count=6
[DEBUG] [1575679192.648960894] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679192.649198647] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002522, min=0.002228, max=0.002620, std_dev=0.000157, count=7
[DEBUG] [1575679193.666881951] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679193.666952070] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002534, min=0.002228, max=0.002620, std_dev=0.000151, count=8
[DEBUG] [1575679194.682101166] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679194.682244856] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002544, min=0.002228, max=0.002620, std_dev=0.000145, count=9
[DEBUG] [1575679195.651991164] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679195.652085111] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002552, min=0.002228, max=0.002620, std_dev=0.000139, count=10
[DEBUG] [1575679196.715741330] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679196.715811571] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002558, min=0.002228, max=0.002620, std_dev=0.000134, count=11
[DEBUG] [1575679197.680580051] [linuxProcessMemoryCollector]: performPeriodicMeasurement: 0.002620
[DEBUG] [1575679197.680648410] [linuxProcessMemoryCollector]: name=linuxProcessMemoryCollector, measurement_period=1000ms, publishing_topic=not_publishing_yet, publish_period=60000ms, clear_measurements_on_publish_=1, started=true, avg=0.002563, min=0.002228, max=0.002620, std_dev=0.000130, count=12

[codecov]

Codecov Report

Merging #28 into master will increase coverage by 0.16%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #28      +/-   ##
==========================================
+ Coverage   41.88%   42.04%   +0.16%     
==========================================
  Files          23       26       +3     
  Lines         819      880      +61     
  Branches      475      506      +31     
==========================================
+ Hits          343      370      +27     
- Misses         42       50       +8     
- Partials      434      460      +26

Impacted Files	Coverage Δ
...etrics_collector/test_linux_memory_measurement.cpp	30.7% <0%> (-0.25%)	⬇️
...m_metrics_collector/linux_cpu_measurement_node.cpp	36.73% <0%> (ø)	⬆️
...tor/test_linux_process_memory_measurement_node.cpp	41.93% <0%> (ø)
...ollector/linux_process_memory_measurement_node.cpp	33.33% <0%> (ø)
...ollector/linux_process_memory_measurement_node.hpp	100% <0%> (ø)
...llector/src/system_metrics_collector/utilities.cpp	28.88% <0%> (+3.3%)	⬆️
...r/test/system_metrics_collector/test_collector.cpp	43.24% <0%> (+5.74%)	⬆️

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[dabonnie]

Review changes WIP, not all have been addressed.