SERVER-56677 Refactor --shutdown handling

1 files changed, 60 insertions, 39 deletions

diff --git a/src/mongo/db/mongod_main.cpp b/src/mongo/db/mongod_main.cpp
index 54b3f7f70bd..a3879a152c6 100644
--- a/src/mongo/db/mongod_main.cpp
+++ b/src/mongo/db/mongod_main.cpp
@@ -842,6 +842,63 @@ MONGO_INITIALIZER_GENERAL(ForkServer, ("EndStartupOptionHandling"), ("default"))
     mongo::forkServerOrDie();
 }
 
+#ifdef __linux__
+/**
+ * Read the pid file from the dbpath for the process ID used by this instance of the server.
+ * Use that process number to kill the running server.
+ *
+ * Equivalent to: `kill -SIGTERM $(cat $DBPATH/mongod.lock)`
+ *
+ * Performs additional checks to make sure the PID as read is reasonable (>= 1)
+ * and can be found in the /proc filesystem.
+ */
+Status shutdownProcessByDBPathPidFile(const std::string& dbpath) {
+    auto pidfile = (boost::filesystem::path(dbpath) / kLockFileBasename.toString()).string();
+    if (!boost::filesystem::exists(pidfile)) {
+        return {ErrorCodes::OperationFailed,
+                str::stream() << "There doesn't seem to be a server running with dbpath: "
+                              << dbpath};
+    }
+
+    pid_t pid;
+    try {
+        std::ifstream f(pidfile.c_str());
+        f >> pid;
+    } catch (const std::exception& ex) {
+        return {ErrorCodes::OperationFailed,
+                str::stream() << "Error reading pid from lock file [" << pidfile
+                              << "]: " << ex.what()};
+    }
+
+    if (pid <= 0) {
+        return {ErrorCodes::OperationFailed,
+                str::stream() << "Invalid process ID '" << pid
+                              << "' read from pidfile: " << pidfile};
+    }
+
+    std::string procPath = str::stream() << "/proc/" << pid;
+    if (!boost::filesystem::exists(procPath)) {
+        return {ErrorCodes::OperationFailed,
+                str::stream() << "Process ID '" << pid << "' read from pidfile '" << pidfile
+                              << "' does not appear to be running"};
+    }
+
+    std::cout << "Killing process with pid: " << pid << std::endl;
+    int ret = kill(pid, SIGTERM);
+    if (ret) {
+        int e = errno;
+        return {ErrorCodes::OperationFailed,
+                str::stream() << "Failed to kill process: " << errnoWithDescription(e)};
+    }
+
+    while (boost::filesystem::exists(pidfile)) {
+        sleepsecs(1);
+    }
+
+    return Status::OK();
+}
+#endif  // __linux__
+
 /*
  * This function should contain the startup "actions" that we take based on the startup config.
  * It is intended to separate the actions from "storage" and "validation" of our startup
@@ -883,48 +940,12 @@ void startupConfigActions(const std::vector<std::string>& args) {
 #ifdef __linux__
     if (moe::startupOptionsParsed.count("shutdown") &&
         moe::startupOptionsParsed["shutdown"].as<bool>() == true) {
-        bool failed = false;
-
-        std::string name =
-            (boost::filesystem::path(storageGlobalParams.dbpath) / kLockFileBasename.toString())
-                .string();
-        if (!boost::filesystem::exists(name) || boost::filesystem::file_size(name) == 0)
-            failed = true;
-
-        pid_t pid;
-        std::string procPath;
-        if (!failed) {
-            try {
-                std::ifstream f(name.c_str());
-                f >> pid;
-                procPath = (str::stream() << "/proc/" << pid);
-                if (!boost::filesystem::exists(procPath))
-                    failed = true;
-            } catch (const std::exception& e) {
-                std::cerr << "Error reading pid from lock file [" << name << "]: " << e.what()
-                          << endl;
-                failed = true;
-            }
-        }
-
-        if (failed) {
-            std::cerr << "There doesn't seem to be a server running with dbpath: "
-                      << storageGlobalParams.dbpath << std::endl;
-            quickExit(EXIT_FAILURE);
-        }
-
-        std::cout << "killing process with pid: " << pid << endl;
-        int ret = kill(pid, SIGTERM);
-        if (ret) {
-            int e = errno;
-            std::cerr << "failed to kill process: " << errnoWithDescription(e) << endl;
+        auto status = shutdownProcessByDBPathPidFile(storageGlobalParams.dbpath);
+        if (!status.isOK()) {
+            std::cerr << status.reason() << std::endl;
             quickExit(EXIT_FAILURE);
         }
 
-        while (boost::filesystem::exists(procPath)) {
-            sleepsecs(1);
-        }
-
         quickExit(EXIT_SUCCESS);
     }
 #endif