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Don't race in FreeBSD devstat collector

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Querying the number of devices separately from the device list itself is
racy. Devices may be added or removed between the two calls; and removed
devices would lead to a segfault.
pull/396/head
Dominik Honnef 8 years ago
parent 5e220c1665
commit ea55d0f5cb
3 changed files with 71 additions and 72 deletions
Show Stats Download Patch File Download Diff File

99
collector/devstat_freebsd.c
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@ -9,66 +9,59 @@
#include <string.h>
#include <devstat_freebsd.h>
int _get_ndevs() {
struct statinfo current;
struct devinfo info = {};
current.dinfo = &info;
devstat_checkversion(NULL);
if (devstat_getdevs(NULL, &current) == -1)
return -1;
return current.dinfo->numdevs;
}
Stats _get_stats(int i) {
int _get_stats(Stats **stats) {
struct statinfo current;
struct devinfo info = {};
current.dinfo = &info;
devstat_getdevs(NULL, &current);
if (devstat_getdevs(NULL, &current) == -1) {
return -1;
}
Stats stats;
uint64_t bytes_read, bytes_write, bytes_free;
uint64_t transfers_other, transfers_read, transfers_write, transfers_free;
long double duration_other, duration_read, duration_write, duration_free;
long double busy_time;
uint64_t blocks;
Stats *p = (Stats*)calloc(current.dinfo->numdevs, sizeof(Stats));
for (int i = 0; i < current.dinfo->numdevs; i++) {
uint64_t bytes_read, bytes_write, bytes_free;
uint64_t transfers_other, transfers_read, transfers_write, transfers_free;
long double duration_other, duration_read, duration_write, duration_free;
long double busy_time;
uint64_t blocks;
strcpy(stats.device, current.dinfo->devices[i].device_name);
stats.unit = current.dinfo->devices[i].unit_number;
devstat_compute_statistics(&current.dinfo->devices[i],
NULL,
1.0,
DSM_TOTAL_BYTES_READ, &bytes_read,
DSM_TOTAL_BYTES_WRITE, &bytes_write,
DSM_TOTAL_BYTES_FREE, &bytes_free,
DSM_TOTAL_TRANSFERS_OTHER, &transfers_other,
DSM_TOTAL_TRANSFERS_READ, &transfers_read,
DSM_TOTAL_TRANSFERS_WRITE, &transfers_write,
DSM_TOTAL_TRANSFERS_FREE, &transfers_free,
DSM_TOTAL_DURATION_OTHER, &duration_other,
DSM_TOTAL_DURATION_READ, &duration_read,
DSM_TOTAL_DURATION_WRITE, &duration_write,
DSM_TOTAL_DURATION_FREE, &duration_free,
DSM_TOTAL_BUSY_TIME, &busy_time,
DSM_TOTAL_BLOCKS, &blocks,
DSM_NONE);
strcpy(p[i].device, current.dinfo->devices[i].device_name);
p[i].unit = current.dinfo->devices[i].unit_number;
devstat_compute_statistics(&current.dinfo->devices[i],
NULL,
1.0,
DSM_TOTAL_BYTES_READ, &bytes_read,
DSM_TOTAL_BYTES_WRITE, &bytes_write,
DSM_TOTAL_BYTES_FREE, &bytes_free,
DSM_TOTAL_TRANSFERS_OTHER, &transfers_other,
DSM_TOTAL_TRANSFERS_READ, &transfers_read,
DSM_TOTAL_TRANSFERS_WRITE, &transfers_write,
DSM_TOTAL_TRANSFERS_FREE, &transfers_free,
DSM_TOTAL_DURATION_OTHER, &duration_other,
DSM_TOTAL_DURATION_READ, &duration_read,
DSM_TOTAL_DURATION_WRITE, &duration_write,
DSM_TOTAL_DURATION_FREE, &duration_free,
DSM_TOTAL_BUSY_TIME, &busy_time,
DSM_TOTAL_BLOCKS, &blocks,
DSM_NONE);
stats.bytes.read = bytes_read;
stats.bytes.write = bytes_write;
stats.bytes.free = bytes_free;
stats.transfers.other = transfers_other;
stats.transfers.read = transfers_read;
stats.transfers.write = transfers_write;
stats.transfers.free = transfers_free;
stats.duration.other = duration_other;
stats.duration.read = duration_read;
stats.duration.write = duration_write;
stats.duration.free = duration_free;
stats.busyTime = busy_time;
stats.blocks = blocks;
p[i].bytes.read = bytes_read;
p[i].bytes.write = bytes_write;
p[i].bytes.free = bytes_free;
p[i].transfers.other = transfers_other;
p[i].transfers.read = transfers_read;
p[i].transfers.write = transfers_write;
p[i].transfers.free = transfers_free;
p[i].duration.other = duration_other;
p[i].duration.read = duration_read;
p[i].duration.write = duration_write;
p[i].duration.free = duration_free;
p[i].busyTime = busy_time;
p[i].blocks = blocks;
}
return stats;
*stats = p;
return current.dinfo->numdevs;
}

42
collector/devstat_freebsd.go
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@ -18,6 +18,7 @@ package collector
import (
"errors"
"fmt"
"unsafe"
"github.com/prometheus/client_golang/prometheus"
)
@ -75,25 +76,30 @@ func NewDevstatCollector() (Collector, error) {
}, nil
}
func (c *devstatCollector) Update(ch chan<- prometheus.Metric) (err error) {
count := C._get_ndevs()
if count == -1 {
return errors.New("devstat_getdevs() failed")
func (c *devstatCollector) Update(ch chan<- prometheus.Metric) error {
var stats *C.Stats
n := C._get_stats(&stats)
if n == -1 {
return errors.New("devstat_getdevs failed")
}
for i := C.int(0); i < count; i++ {
stats := C._get_stats(i)
device := fmt.Sprintf("%s%d", C.GoString(&stats.device[0]), stats.unit)
ch <- c.bytes.mustNewConstMetric(float64(stats.bytes.read), device, "read")
ch <- c.bytes.mustNewConstMetric(float64(stats.bytes.write), device, "write")
ch <- c.transfers.mustNewConstMetric(float64(stats.transfers.other), device, "other")
ch <- c.transfers.mustNewConstMetric(float64(stats.transfers.read), device, "read")
ch <- c.transfers.mustNewConstMetric(float64(stats.transfers.write), device, "write")
ch <- c.duration.mustNewConstMetric(float64(stats.duration.other), device, "other")
ch <- c.duration.mustNewConstMetric(float64(stats.duration.read), device, "read")
ch <- c.duration.mustNewConstMetric(float64(stats.duration.write), device, "write")
ch <- c.busyTime.mustNewConstMetric(float64(stats.busyTime), device)
ch <- c.blocks.mustNewConstMetric(float64(stats.blocks), device)
base := unsafe.Pointer(stats)
for i := C.int(0); i < n; i++ {
offset := i * C.int(C.sizeof_Stats)
stat := (*C.Stats)(unsafe.Pointer(uintptr(base) + uintptr(offset)))
device := fmt.Sprintf("%s%d", C.GoString(&stat.device[0]), stat.unit)
ch <- c.bytes.mustNewConstMetric(float64(stat.bytes.read), device, "read")
ch <- c.bytes.mustNewConstMetric(float64(stat.bytes.write), device, "write")
ch <- c.transfers.mustNewConstMetric(float64(stat.transfers.other), device, "other")
ch <- c.transfers.mustNewConstMetric(float64(stat.transfers.read), device, "read")
ch <- c.transfers.mustNewConstMetric(float64(stat.transfers.write), device, "write")
ch <- c.duration.mustNewConstMetric(float64(stat.duration.other), device, "other")
ch <- c.duration.mustNewConstMetric(float64(stat.duration.read), device, "read")
ch <- c.duration.mustNewConstMetric(float64(stat.duration.write), device, "write")
ch <- c.busyTime.mustNewConstMetric(float64(stat.busyTime), device)
ch <- c.blocks.mustNewConstMetric(float64(stat.blocks), device)
}
return err
C.free(unsafe.Pointer(stats))
return nil
}

2
collector/devstat_freebsd.h
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@ -38,4 +38,4 @@ typedef struct {
int _get_ndevs();
Stats _get_stats(int i);
int _get_stats(Stats **stats);

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