Add ZFS freebsd per dataset stats (prometheus#2753)

* Rename parsePoolObjsetFile to parseLinuxPoolObjsetFile to better reflect
it's scope
* Create a new parseFreeBSDPoolObjsetStats function, to generate a list
of per pool metrics to be queried via sysctl


---------

Signed-off-by: Conall O'Brien <conall@conall.net>

collector/exec_bsd.go

@@ -49,31 +49,37 @@ func NewExecCollector(logger log.Logger) (Collector, error) {
 				name:        "exec_context_switches_total",
 				description: "Context switches since system boot.  Resets at architecture unsigned integer.",
 				mib:         "vm.stats.sys.v_swtch",
+				labels:      nil,
 			},
 			{
 				name:        "exec_traps_total",
 				description: "Traps since system boot.  Resets at architecture unsigned integer.",
 				mib:         "vm.stats.sys.v_trap",
+				labels:      nil,
 			},
 			{
 				name:        "exec_system_calls_total",
 				description: "System calls since system boot.  Resets at architecture unsigned integer.",
 				mib:         "vm.stats.sys.v_syscall",
 			},
+			labels: nil,
 			{
 				name:        "exec_device_interrupts_total",
 				description: "Device interrupts since system boot.  Resets at architecture unsigned integer.",
 				mib:         "vm.stats.sys.v_intr",
+				labels:      nil,
 			},
 			{
 				name:        "exec_software_interrupts_total",
 				description: "Software interrupts since system boot.  Resets at architecture unsigned integer.",
 				mib:         "vm.stats.sys.v_soft",
+				labels:      nil,
 			},
 			{
 				name:        "exec_forks_total",
 				description: "Number of fork() calls since system boot.  Resets at architecture unsigned integer.",
 				mib:         "vm.stats.vm.v_forks",
+				labels:      nil,
 			},
 		},
 		logger: logger,

collector/memory_bsd.go

@@ -69,61 +69,71 @@ func NewMemoryCollector(logger log.Logger) (Collector, error) {
 				description: "Recently used by userland",
 				mib:         "vm.stats.vm.v_active_count",
 				conversion:  fromPage,
+				labels:      nil,
 			},
 			{
 				name:        "inactive_bytes",
 				description: "Not recently used by userland",
 				mib:         "vm.stats.vm.v_inactive_count",
 				conversion:  fromPage,
+				labels:      nil,
 			},
 			{
 				name:        "wired_bytes",
 				description: "Locked in memory by kernel, mlock, etc",
 				mib:         "vm.stats.vm.v_wire_count",
 				conversion:  fromPage,
+				labels:      nil,
 			},
 			{
 				name:        "user_wired_bytes",
 				description: "Locked in memory by user, mlock, etc",
 				mib:         "vm.stats.vm.v_user_wire_count",
 				conversion:  fromPage,
 				dataType:    bsdSysctlTypeCLong,
+				labels:      nil,
 			},
 			{
 				name:        "cache_bytes",
 				description: "Almost free, backed by swap or files, available for re-allocation",
 				mib:         "vm.stats.vm.v_cache_count",
 				conversion:  fromPage,
+				labels:      nil,
 			},
 			{
 				name:        "buffer_bytes",
 				description: "Disk IO Cache entries for non ZFS filesystems, only usable by kernel",
 				mib:         "vfs.bufspace",
 				dataType:    bsdSysctlTypeCLong,
+				labels:      nil,
 			},
 			{
 				name:        "free_bytes",
 				description: "Unallocated, available for allocation",
 				mib:         "vm.stats.vm.v_free_count",
 				conversion:  fromPage,
+				labels:      nil,
 			},
 			{
 				name:        "laundry_bytes",
 				description: "Dirty not recently used by userland",
 				mib:         "vm.stats.vm.v_laundry_count",
 				conversion:  fromPage,
+				labels:      nil,
 			},
 			{
 				name:        "size_bytes",
 				description: "Total physical memory size",
 				mib:         "vm.stats.vm.v_page_count",
 				conversion:  fromPage,
+				labels:      nil,
 			},
 			{
 				name:        "swap_size_bytes",
 				description: "Total swap memory size",
 				mib:         mibSwapTotal,
 				dataType:    bsdSysctlTypeUint64,
+				labels:      nil,
 			},
 			// Descriptions via: top(1)
 			{
@@ -132,13 +142,15 @@ func NewMemoryCollector(logger log.Logger) (Collector, error) {
 				mib:         "vm.stats.vm.v_swappgsin",
 				valueType:   prometheus.CounterValue,
 				conversion:  fromPage,
+				labels:      nil,
 			},
 			{
 				name:        "swap_out_bytes_total",
 				description: "Bytes paged out to swap devices",
 				mib:         "vm.stats.vm.v_swappgsout",
 				valueType:   prometheus.CounterValue,
 				conversion:  fromPage,
+				labels:      nil,
 			},
 		},
 	}, nil

collector/netisr_freebsd.go

@@ -45,41 +45,47 @@ func NewNetisrCollector(logger log.Logger) (Collector, error) {
 				mib:         "net.isr.numthreads",
 				dataType:    bsdSysctlTypeUint32,
 				valueType:   prometheus.GaugeValue,
+				labels:      nil,
 			},
 			{
 				name:        "maxprot",
 				description: "netisr maximum protocols",
 				mib:         "net.isr.maxprot",
 				dataType:    bsdSysctlTypeUint32,
 				valueType:   prometheus.GaugeValue,
+				labels:      nil,
 			},
 			{
 				name:        "defaultqlimit",
 				description: "netisr default queue limit",
 				mib:         "net.isr.defaultqlimit",
 				dataType:    bsdSysctlTypeUint32,
 				valueType:   prometheus.GaugeValue,
+				labels:      nil,
 			},
 			{
 				name:        "maxqlimit",
 				description: "netisr maximum queue limit",
 				mib:         "net.isr.maxqlimit",
 				dataType:    bsdSysctlTypeUint32,
 				valueType:   prometheus.GaugeValue,
+				labels:      nil,
 			},
 			{
 				name:        "bindthreads",
 				description: "netisr threads bound to CPUs",
 				mib:         "net.isr.bindthreads",
 				dataType:    bsdSysctlTypeUint32,
 				valueType:   prometheus.GaugeValue,
+				labels:      nil,
 			},
 			{
 				name:        "maxthreads",
 				description: "netisr maximum thread count",
 				mib:         "net.isr.maxthreads",
 				dataType:    bsdSysctlTypeUint32,
 				valueType:   prometheus.GaugeValue,
+				labels:      nil,
 			},
 		},
 		logger: logger,

collector/sysctl_bsd.go

@@ -59,6 +59,9 @@ type bsdSysctl struct {
 
 	// Post-retrieval conversion hooks
 	conversion func(float64) float64
+
+	// Prometheus labels
+	labels prometheus.Labels
 }
 
 func (b bsdSysctl) Value() (float64, error) {