StorageMetrics Class Reference

Public Member Functions
	StorageMetrics (std::shared_ptr< ZKWrapper > zkWrapper_)
float	usedSpaceFraction ()
float	usedSpace ()
float	blocksPerDataNodeSD ()
int	replicationRecoverySpeed ()
float	degenerateRead (std::string file, std::string destination, std::vector< std::pair< std::string, std::string >> targetDatanodes)

Static Public Member Functions
static void	watcher_replicate (zhandle_t *zzh, int type, int state, const char *path, void *watcherCtx)

Constructor & Destructor Documentation

StorageMetrics::StorageMetrics ( std::shared_ptr< ZKWrapper >  zkWrapper_ )

explicit

Constructor

Parameters

numDatanodes_	the number of datanodes, known by the caller test. This can be changed to be variable size later if needed.
zkWrapper_	the zkWrapper

Member Function Documentation

float StorageMetrics::blocksPerDataNodeSD

(

)

Counts number of used blocks on each datanode, and takes the standard deviation of that distribution.

Returns

The standard deviation of the blocks per datanode

float StorageMetrics::degenerateRead	(	std::string	file,
		std::string	destination,
		std::vector< std::pair< std::string, std::string >>	targetDatanodes
	)

Measures how long a read takes while a data block is being recovered.

Prints the resulting time.

Note that files under replication have no degenerate read. The degenerate case is the file being unreadable. Files under EC must have a downed data block (not parity block) for the degenerate read case. Keep that in mind when passing in target DataNodes

Logging level must be set to 9 before calling this function.

Parameters

file	The file path to read.
destination	The file name for writing cat output
targetDatanodes	first: unix process name of a datanode to kill second: cliArgs for restarting that datanode.

Returns

0 on success, 1 on error

int StorageMetrics::replicationRecoverySpeed

(

)

Measures the time for recovering from a DataNode failure.

This method polls the zookeeper work_queues/replication until there are none left. This should only be called from tests with a controlled number of replications.

Prints wall clock time spent in this function using easylogging++

Logging level must be set to 9 before calling this function.

Returns

0 success, -1 error

float StorageMetrics::usedSpace

(

)

Returns the total space used.

Returns

totalUsedSpace

float StorageMetrics::usedSpaceFraction

(

)

Returns the proportion of space used.

Returns

totalUsedSpace / totalSpace

void StorageMetrics::watcher_replicate ( zhandle_t *  zzh, int  type, int  state, const char *  path, void *  watcherCtx  )

static

watcher function to set on /work_queues/replicate.

Parameters

zzh	unused
type	unused
state	unused
path	Path to the znode to watch.
watcherCtx	"this"

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The documentation for this class was generated from the following files:

• storage/include/StorageMetrics.h
• storage/source/StorageMetrics.cc