1 files changed, 88 insertions, 0 deletions
diff --git a/logforwarder/src/apps/vespa-otelcol-start/child-handler.cpp b/logforwarder/src/apps/vespa-otelcol-start/child-handler.cpp
new file mode 100644
index 00000000000..46ac3bea60e
--- /dev/null
+++ b/logforwarder/src/apps/vespa-otelcol-start/child-handler.cpp
@@ -0,0 +1,88 @@
+// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include "child-handler.h"
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <sys/wait.h>
+#include <vector>
+#include <string>
+#include <cstdlib>
+
+#include <vespa/log/log.h>
+LOG_SETUP(".child-handler");
+
+ChildHandler::ChildHandler() : _childRunning(false), _childPid(0) {}
+
+ChildHandler::~ChildHandler() = default;
+
+bool ChildHandler::checkChild() {
+    if (! _childRunning) return true;
+    int waitStatus = 0;
+    int r = waitpid(_childPid, &waitStatus, WNOHANG);
+    if (r == 0) {
+        return false;
+    }
+    if (r < 0) {
+        perror("waitpid");
+        // XXX how to handle?
+        return false;
+    }
+    _childRunning = false;
+    if (WIFEXITED(waitStatus) && WEXITSTATUS(waitStatus) == 0) {
+        // all OK
+        LOG(info, "child ran ok, exit status 0");
+    } else if (WIFEXITED(waitStatus)) {
+        LOG(warning, "child failed (exit status %d)", WEXITSTATUS(waitStatus));
+    } else if (WIFSIGNALED(waitStatus)) {
+        if (_terminating) {
+            LOG(info, "child terminated (using signal %d)", WTERMSIG(waitStatus));
+        } else {
+            LOG(warning, "child failed (exit on signal %d)", WTERMSIG(waitStatus));
+        }
+    } else {
+        LOG(warning, "child failed (abnormal exit status %d)", waitStatus);
+    }
+    return true;
+}
+
+void ChildHandler::startChild(const std::string &progPath, const std::string &cfPath) {
+    _terminating = false;
+    LOG(info, "startChild '%s' '%s'", progPath.c_str(), cfPath.c_str());
+    pid_t child = fork();
+    if (child == -1) {
+        perror("fork()");
+        return;
+    }
+    if (child == 0) {
+        std::string cfArg{"--config=file:" + cfPath};
+        const char *cargv[] = { progPath.c_str(), cfArg.c_str(), nullptr };
+        execv(progPath.c_str(), const_cast<char **>(cargv));
+        // if execv fails:
+        perror(progPath.c_str());
+        std::_Exit(1);
+    }
+    LOG(info, "child running with pid %d", (int)child);
+    _childRunning = true;
+    _childPid = child;
+}
+
+void ChildHandler::stopChild() {
+    if (! _childRunning) return;
+    LOG(info, "stopChild");
+    _terminating = true;
+    kill(_childPid, SIGTERM);
+    for (int retry = 0; retry < 10; ++retry) {
+        if (checkChild()) return;
+        usleep(12500 + retry * 20000);
+    }
+    kill(_childPid, SIGKILL);
+    for (int retry = 0; retry < 10; ++retry) {
+        if (checkChild()) return;
+        usleep(12500 + retry * 20000);
+    }
+    LOG(error, "Could not terminete child process %d", _childPid);
+}