SnmpQuery runtime cache (#15512)

* SnmpQuery runtime cache
Optionally cache the SnmpResponse from queries for the rest of the runtime.
It would be nice to have cache hits for these to help prevent wasting memory caching data that is only used once.
Key data must match: device, context, options, oids

* Apply fixes from StyleCI

* Add command to the cache key

* Caching in the wrong spot, cache individual commands...

* Apply fixes from StyleCI

---------

Co-authored-by: StyleCI Bot <bot@styleci.io>

LibreNMS/Data/Source/NetSnmpQuery.php

@@ -30,6 +30,7 @@ use App\Models\Eventlog;
 use App\Polling\Measure\Measurement;
 use DeviceCache;
 use Illuminate\Support\Arr;
+use Illuminate\Support\Facades\Cache;
 use Illuminate\Support\Str;
 use LibreNMS\Config;
 use LibreNMS\Enum\Severity;
@@ -82,6 +83,7 @@ class NetSnmpQuery implements SnmpQueryInterface
     private array|string $options = [self::DEFAULT_FLAGS];
     private Device $device;
     private bool $abort = false;
+    private bool $cache = false;
     // defaults for net-snmp https://net-snmp.sourceforge.io/docs/man/snmpcmd.html
     private array $mibs = ['SNMPv2-TC', 'SNMPv2-MIB', 'IF-MIB', 'IP-MIB', 'TCP-MIB', 'UDP-MIB', 'NET-SNMP-VACM-MIB'];
 
@@ -126,6 +128,13 @@ class NetSnmpQuery implements SnmpQueryInterface
         return $this;
     }
 
+    public function cache(): SnmpQueryInterface
+    {
+        $this->cache = true;
+
+        return $this;
+    }
+
     /**
      * Set a context for the snmp query
      * This is most commonly used to fetch alternate sets of data, such as different VRFs
@@ -201,6 +210,18 @@ class NetSnmpQuery implements SnmpQueryInterface
         return $this;
     }
 
+    /**
+     * Output all OIDs numerically
+     */
+    public function numericIndex(bool $numericIndex = true): SnmpQueryInterface
+    {
+        $this->options = $numericIndex
+            ? array_merge($this->options, ['-Ob'])
+            : array_diff($this->options, ['-Ob']);
+
+        return $this;
+    }
+
     /**
      * Hide MIB in output
      */
@@ -373,7 +394,8 @@ class NetSnmpQuery implements SnmpQueryInterface
 
             // if abort on failure is set, return after first failure
             if ($this->abort && ! $response->isValid()) {
-                Log::debug("SNMP failed walking $oid of " . implode(',', $oids) . ' aborting.');
+                $oid_list = implode(',', array_map(fn ($group) => implode(',', $group), $oids));
+                Log::debug("SNMP failed walking $oid of $oid_list aborting.");
 
                 return $response;
             }
@@ -384,25 +406,30 @@ class NetSnmpQuery implements SnmpQueryInterface
 
     private function exec(string $command, array $oids): SnmpResponse
     {
-        $measure = Measurement::start($command);
+        // use runtime(array) cache if requested. The 'null' driver will simply return the value without caching
+        $driver = $this->cache ? 'array' : 'null';
+        $key = $this->cache ? $this->getCacheKey($command, $oids) : '';
 
-        $proc = new Process($this->buildCli($command, $oids));
-        $proc->setTimeout(Config::get('snmp.exec_timeout', 1200));
+        return Cache::driver($driver)->rememberForever($key, function () use ($command, $oids) {
+            $measure = Measurement::start($command);
+            $proc = new Process($this->buildCli($command, $oids));
+            $proc->setTimeout(Config::get('snmp.exec_timeout', 1200));
 
-        $this->logCommand($proc->getCommandLine());
+            $this->logCommand($proc->getCommandLine());
 
-        $proc->run();
-        $exitCode = $proc->getExitCode();
-        $output = $proc->getOutput();
-        $stderr = $proc->getErrorOutput();
+            $proc->run();
+            $exitCode = $proc->getExitCode();
+            $output = $proc->getOutput();
+            $stderr = $proc->getErrorOutput();
 
-        // check exit code and log possible bad auth
-        $this->checkExitCode($exitCode, $stderr);
-        $this->logOutput($output, $stderr);
+            // check exit code and log possible bad auth
+            $this->checkExitCode($exitCode, $stderr);
+            $this->logOutput($output, $stderr);
 
-        $measure->manager()->recordSnmp($measure->end());
+            $measure->manager()->recordSnmp($measure->end());
 
-        return new SnmpResponse($output, $stderr, $exitCode);
+            return new SnmpResponse($output, $stderr, $exitCode);
+        });
     }
 
     private function initCommand(string $binary, array $oids): array
@@ -513,4 +540,12 @@ class NetSnmpQuery implements SnmpQueryInterface
     {
         return is_string($oid) ? explode(' ', $oid) : $oid;
     }
+
+    private function getCacheKey(string $type, array $oids): string
+    {
+        $oids = implode(',', $oids);
+        $options = implode(',', $this->options);
+
+        return "$type|{$this->device->hostname}|$this->context|$oids|$options";
+    }
 }

LibreNMS/Data/Source/SnmpQueryInterface.php

@@ -46,6 +46,11 @@ interface SnmpQueryInterface
      */
     public function deviceArray(array $device): SnmpQueryInterface;
 
+    /**
+     * Cache the data for the rest of the runtime (or retrieve from cache if available)
+     */
+    public function cache(): SnmpQueryInterface;
+
     /**
      * Set a context for the snmp query
      * This is most commonly used to fetch alternate sets of data, such as different VRFs
@@ -81,6 +86,11 @@ interface SnmpQueryInterface
      */
     public function numeric(bool $numeric = true): SnmpQueryInterface;
 
+    /**
+     * Output indexes only as numeric
+     */
+    public function numericIndex(bool $numericIndex = true): SnmpQueryInterface;
+
     /**
      * Hide MIB in output
      */

LibreNMS/Data/Source/SnmpResponse.php

@@ -286,4 +286,9 @@ class SnmpResponse
         // regular oid
         return explode('.', $key);
     }
+
+    public function __sleep()
+    {
+        return ['raw', 'exitCode', 'stderr'];
+    }
 }

tests/Mocks/SnmpQueryMock.php

@@ -73,6 +73,11 @@ class SnmpQueryMock implements SnmpQueryInterface
         return $this;
     }
 
+    public function cache(): SnmpQueryInterface
+    {
+        return $this; // ignore, always cached
+    }
+
     public function context(string $context): SnmpQueryInterface
     {
         $this->context = $context;
@@ -117,6 +122,14 @@ class SnmpQueryMock implements SnmpQueryInterface
         return $this;
     }
 
+    public function numericIndex(bool $numericIndex = true): SnmpQueryInterface
+    {
+        // TODO: Implement numericIndex() method
+        Log::error('numericIndex not implemented in SnmpQueryMock');
+
+        return $this;
+    }
+
     public function hideMib(): SnmpQueryInterface
     {
         $this->hideMib = true;