feat: dvfs agent interface

nextflow/plugins/nf-k8s/src/main/nextflow/k8s/K8sDVFSClient.groovy

@@ -0,0 +1,68 @@
+package nextflow.k8s
+
+import groovy.util.logging.Slf4j
+
+import java.net.http.HttpClient
+import java.net.http.HttpRequest
+import java.net.http.HttpResponse
+
+/**
+ * The DVFS client uses the deployed DVFS agents to control the operating frequency of the worker nodes.
+ */
+@Slf4j
+class K8sDVFSClient {
+    private HttpClient httpClient
+
+    K8sDVFSClient() {
+        this.httpClient = HttpClient.newBuilder().build()
+    }
+
+    OptionalInt getNodeCurrentFrequency(String node) {
+        log.debug("Getting current frequency of node ${node}")
+        return getNodeFrequency(node, "current")
+    }
+
+    OptionalInt getNodeMaxFrequency(String node) {
+        log.debug("Getting max frequency of node ${node}")
+        return getNodeFrequency(node, "max")
+    }
+
+    OptionalInt getNodeMinFrequency(String node) {
+        log.debug("Getting min frequency of node ${node}")
+        return getNodeFrequency(node, "min")
+    }
+
+    private OptionalInt getNodeFrequency(String node, String endpoint) {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("http://${nodeName}/cpu/frequency/${endpoint}"))
+            .GET()
+            .build()
+        HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString())
+        if (response.statusCode() != 200) {
+            log.error("Request GET ${request.uri().toString()} returned ${response.statusCode()}")
+            return OptionalInt.empty()
+        }
+        try {
+            double parsed = Double.parseDouble(response.body())
+            return OptionalInt.of(parsed)
+        } catch (NumberFormatException ex) {
+            log.error("Unexpected response ${response.body()} - ${ex.message}")
+            return OptionalInt.empty()
+        }
+    }
+
+    boolean setNodeFrequency(String node, int frequency) {
+        String body = String.valueOf(frequency)
+
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("http://${nodeName}/cpu/frequency/current"))
+            .PUT(HttpRequ3est.BodyPublishers.ofString(body))
+            .build()
+        HttpResponse<Void> response = httpClient.send(request, HttpResponse.BodyHandlers.discarding())
+        if (response.statusCode() != 200) {
+            log.error("Request PUT ${request.uri().toString()} returned ${response.statusCode()}")
+            return false
+        }
+        return true
+    }
+}