snmp: use a shared global translation cache
Prevents the same data from being looked up multiple times. Also prevents multiple simultaneous lookups. closes #2115 closes #2104
This commit is contained in:
Patrick Hemmer
Cameron Sparr
parent
bed09e0a9c
commit
3da3a22791
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@ -15,6 +15,7 @@
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### Bugfixes
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- [#2007](https://github.com/influxdata/telegraf/issues/2007): Make snmptranslate not required when using numeric OID.
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- [#2104](https://github.com/influxdata/telegraf/issues/2104): Add a global snmp translation cache.
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## v1.1.1 [2016-11-14]
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@ -8,6 +8,7 @@ import (
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"os/exec"
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"strconv"
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"strings"
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"sync"
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"time"
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"github.com/influxdata/telegraf"
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@ -199,65 +200,22 @@ func (t *Table) init() error {
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return nil
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}
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// init() populates Fields if a table OID is provided.
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// initBuild initializes the table if it has an OID configured. If so, the
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// net-snmp tools will be used to look up the OID and auto-populate the table's
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// fields.
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func (t *Table) initBuild() error {
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if t.Oid == "" {
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return nil
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}
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mibName, _, oidText, _, err := snmpTranslate(t.Oid)
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_, _, oidText, fields, err := snmpTable(t.Oid)
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if err != nil {
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return Errorf(err, "translating %s", t.Oid)
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return Errorf(err, "initializing table %s", t.Oid)
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}
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if t.Name == "" {
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t.Name = oidText
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}
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mibPrefix := mibName + "::"
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oidFullName := mibPrefix + oidText
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// first attempt to get the table's tags
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tagOids := map[string]struct{}{}
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// We have to guess that the "entry" oid is `t.Oid+".1"`. snmptable and snmptranslate don't seem to have a way to provide the info.
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if out, err := execCmd("snmptranslate", "-Td", oidFullName+".1"); err == nil {
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lines := bytes.Split(out, []byte{'\n'})
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for _, line := range lines {
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if !bytes.HasPrefix(line, []byte(" INDEX")) {
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continue
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}
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i := bytes.Index(line, []byte("{ "))
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if i == -1 { // parse error
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continue
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}
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line = line[i+2:]
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i = bytes.Index(line, []byte(" }"))
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if i == -1 { // parse error
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continue
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}
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line = line[:i]
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for _, col := range bytes.Split(line, []byte(", ")) {
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tagOids[mibPrefix+string(col)] = struct{}{}
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}
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}
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}
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// this won't actually try to run a query. The `-Ch` will just cause it to dump headers.
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out, err := execCmd("snmptable", "-Ch", "-Cl", "-c", "public", "127.0.0.1", oidFullName)
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if err != nil {
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return Errorf(err, "getting table columns for %s", t.Oid)
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}
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cols := bytes.SplitN(out, []byte{'\n'}, 2)[0]
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if len(cols) == 0 {
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return fmt.Errorf("unable to get columns for table %s", t.Oid)
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}
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for _, col := range bytes.Split(cols, []byte{' '}) {
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if len(col) == 0 {
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continue
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}
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col := string(col)
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_, isTag := tagOids[mibPrefix+col]
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t.Fields = append(t.Fields, Field{Name: col, Oid: mibPrefix + col, IsTag: isTag})
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}
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t.Fields = append(t.Fields, fields...)
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return nil
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}
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@ -841,8 +799,131 @@ func fieldConvert(conv string, v interface{}) (interface{}, error) {
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return nil, fmt.Errorf("invalid conversion type '%s'", conv)
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}
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type snmpTableCache struct {
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mibName string
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oidNum string
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oidText string
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fields []Field
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err error
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}
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var snmpTableCaches map[string]snmpTableCache
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var snmpTableCachesLock sync.Mutex
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// snmpTable resolves the given OID as a table, providing information about the
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// table and fields within.
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func snmpTable(oid string) (mibName string, oidNum string, oidText string, fields []Field, err error) {
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snmpTableCachesLock.Lock()
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if snmpTableCaches == nil {
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snmpTableCaches = map[string]snmpTableCache{}
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}
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var stc snmpTableCache
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var ok bool
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if stc, ok = snmpTableCaches[oid]; !ok {
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stc.mibName, stc.oidNum, stc.oidText, stc.fields, stc.err = snmpTableCall(oid)
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snmpTableCaches[oid] = stc
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}
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snmpTableCachesLock.Unlock()
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return stc.mibName, stc.oidNum, stc.oidText, stc.fields, stc.err
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}
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func snmpTableCall(oid string) (mibName string, oidNum string, oidText string, fields []Field, err error) {
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mibName, oidNum, oidText, _, err = snmpTranslate(oid)
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if err != nil {
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return "", "", "", nil, Errorf(err, "translating")
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}
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mibPrefix := mibName + "::"
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oidFullName := mibPrefix + oidText
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// first attempt to get the table's tags
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tagOids := map[string]struct{}{}
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// We have to guess that the "entry" oid is `oid+".1"`. snmptable and snmptranslate don't seem to have a way to provide the info.
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if out, err := execCmd("snmptranslate", "-Td", oidFullName+".1"); err == nil {
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lines := bytes.Split(out, []byte{'\n'})
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for _, line := range lines {
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if !bytes.HasPrefix(line, []byte(" INDEX")) {
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continue
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}
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i := bytes.Index(line, []byte("{ "))
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if i == -1 { // parse error
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continue
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}
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line = line[i+2:]
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i = bytes.Index(line, []byte(" }"))
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if i == -1 { // parse error
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continue
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}
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line = line[:i]
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for _, col := range bytes.Split(line, []byte(", ")) {
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tagOids[mibPrefix+string(col)] = struct{}{}
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}
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}
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}
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// this won't actually try to run a query. The `-Ch` will just cause it to dump headers.
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out, err := execCmd("snmptable", "-Ch", "-Cl", "-c", "public", "127.0.0.1", oidFullName)
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if err != nil {
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return "", "", "", nil, Errorf(err, "getting table columns")
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}
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cols := bytes.SplitN(out, []byte{'\n'}, 2)[0]
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if len(cols) == 0 {
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return "", "", "", nil, fmt.Errorf("could not find any columns in table")
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}
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for _, col := range bytes.Split(cols, []byte{' '}) {
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if len(col) == 0 {
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continue
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}
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col := string(col)
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_, isTag := tagOids[mibPrefix+col]
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fields = append(fields, Field{Name: col, Oid: mibPrefix + col, IsTag: isTag})
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}
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return mibName, oidNum, oidText, fields, err
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}
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type snmpTranslateCache struct {
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mibName string
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oidNum string
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oidText string
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conversion string
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err error
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}
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var snmpTranslateCachesLock sync.Mutex
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var snmpTranslateCaches map[string]snmpTranslateCache
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// snmpTranslate resolves the given OID.
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func snmpTranslate(oid string) (mibName string, oidNum string, oidText string, conversion string, err error) {
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snmpTranslateCachesLock.Lock()
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if snmpTranslateCaches == nil {
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snmpTranslateCaches = map[string]snmpTranslateCache{}
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}
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var stc snmpTranslateCache
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var ok bool
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if stc, ok = snmpTranslateCaches[oid]; !ok {
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// This will result in only one call to snmptranslate running at a time.
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// We could speed it up by putting a lock in snmpTranslateCache and then
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// returning it immediately, and multiple callers would then release the
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// snmpTranslateCachesLock and instead wait on the individual
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// snmpTranlsation.Lock to release. But I don't know that the extra complexity
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// is worth it. Especially when it would slam the system pretty hard if lots
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// of lookups are being perfomed.
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stc.mibName, stc.oidNum, stc.oidText, stc.conversion, stc.err = snmpTranslateCall(oid)
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snmpTranslateCaches[oid] = stc
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}
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snmpTranslateCachesLock.Unlock()
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return stc.mibName, stc.oidNum, stc.oidText, stc.conversion, stc.err
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}
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func snmpTranslateCall(oid string) (mibName string, oidNum string, oidText string, conversion string, err error) {
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var out []byte
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if strings.ContainsAny(oid, ":abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ") {
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out, err = execCmd("snmptranslate", "-Td", "-Ob", oid)
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@ -648,6 +648,71 @@ func TestFieldConvert(t *testing.T) {
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}
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}
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func TestSnmpTranslateCache_miss(t *testing.T) {
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snmpTranslateCaches = nil
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oid := "IF-MIB::ifPhysAddress.1"
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mibName, oidNum, oidText, conversion, err := snmpTranslate(oid)
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assert.Len(t, snmpTranslateCaches, 1)
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stc := snmpTranslateCaches[oid]
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require.NotNil(t, stc)
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assert.Equal(t, mibName, stc.mibName)
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assert.Equal(t, oidNum, stc.oidNum)
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assert.Equal(t, oidText, stc.oidText)
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assert.Equal(t, conversion, stc.conversion)
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assert.Equal(t, err, stc.err)
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}
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func TestSnmpTranslateCache_hit(t *testing.T) {
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snmpTranslateCaches = map[string]snmpTranslateCache{
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"foo": snmpTranslateCache{
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mibName: "a",
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oidNum: "b",
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oidText: "c",
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conversion: "d",
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err: fmt.Errorf("e"),
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},
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}
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mibName, oidNum, oidText, conversion, err := snmpTranslate("foo")
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assert.Equal(t, "a", mibName)
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assert.Equal(t, "b", oidNum)
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assert.Equal(t, "c", oidText)
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assert.Equal(t, "d", conversion)
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assert.Equal(t, fmt.Errorf("e"), err)
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snmpTranslateCaches = nil
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}
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func TestSnmpTableCache_miss(t *testing.T) {
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snmpTableCaches = nil
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oid := ".1.0.0.0"
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mibName, oidNum, oidText, fields, err := snmpTable(oid)
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assert.Len(t, snmpTableCaches, 1)
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stc := snmpTableCaches[oid]
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require.NotNil(t, stc)
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assert.Equal(t, mibName, stc.mibName)
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assert.Equal(t, oidNum, stc.oidNum)
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assert.Equal(t, oidText, stc.oidText)
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assert.Equal(t, fields, stc.fields)
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assert.Equal(t, err, stc.err)
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}
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func TestSnmpTableCache_hit(t *testing.T) {
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snmpTableCaches = map[string]snmpTableCache{
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"foo": snmpTableCache{
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mibName: "a",
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oidNum: "b",
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oidText: "c",
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fields: []Field{{Name: "d"}},
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err: fmt.Errorf("e"),
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},
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}
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mibName, oidNum, oidText, fields, err := snmpTable("foo")
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assert.Equal(t, "a", mibName)
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assert.Equal(t, "b", oidNum)
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assert.Equal(t, "c", oidText)
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assert.Equal(t, []Field{{Name: "d"}}, fields)
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assert.Equal(t, fmt.Errorf("e"), err)
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}
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func TestError(t *testing.T) {
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e := fmt.Errorf("nested error")
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err := Errorf(e, "top error %d", 123)
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