8327410: Add hostname option for UL file names

Reviewed-by: jsjolen, dholmes

src/hotspot/share/logging/logConfiguration.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -614,7 +614,7 @@ void LogConfiguration::print_command_line_help(outputStream* out) {
   out->print_cr("Available log outputs:");
   out->print_cr(" stdout/stderr");
   out->print_cr(" file=<filename>");
-  out->print_cr("  If the filename contains %%p and/or %%t, they will expand to the JVM's PID and startup timestamp, respectively.");
+  out->print_cr("  If the filename contains %%p, %%t and/or %%hn, they will expand to the JVM's PID, startup timestamp and host name, respectively.");
   out->cr();
 
   out->print_cr("Available log output options:");

src/hotspot/share/logging/logFileOutput.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -38,6 +38,7 @@ const char* const LogFileOutput::FileOpenMode = "a";
 const char* const LogFileOutput::PidFilenamePlaceholder = "%p";
 const char* const LogFileOutput::TimestampFilenamePlaceholder = "%t";
 const char* const LogFileOutput::TimestampFormat = "%Y-%m-%d_%H-%M-%S";
+const char* const LogFileOutput::HostnameFilenamePlaceholder = "%hn";
 const char* const LogFileOutput::FileSizeOptionKey = "filesize";
 const char* const LogFileOutput::FileCountOptionKey = "filecount";
 char        LogFileOutput::_pid_str[PidBufferSize];
@@ -378,81 +379,81 @@ void LogFileOutput::rotate() {
 char* LogFileOutput::make_file_name(const char* file_name,
                                     const char* pid_string,
                                     const char* timestamp_string) {
+  char hostname_string[HostnameBufferSize];
   char* result = nullptr;
 
-  // Lets start finding out if we have any %d and/or %t in the name.
+  // Lets start finding out if we have any %p, %t and/or %hn in the name.
   // We will only replace the first occurrence of any placeholder
   const char* pid = strstr(file_name, PidFilenamePlaceholder);
   const char* timestamp = strstr(file_name, TimestampFilenamePlaceholder);
+  const char* hostname = strstr(file_name, HostnameFilenamePlaceholder);
 
-  if (pid == nullptr && timestamp == nullptr) {
+  if (pid == nullptr && timestamp == nullptr && hostname == nullptr) {
     // We found no place-holders, return the simple filename
     return os::strdup_check_oom(file_name, mtLogging);
   }
 
   // At least one of the place-holders were found in the file_name
-  const char* first = "";
+  size_t result_len =  strlen(file_name);
-  size_t first_pos = SIZE_MAX;
-  size_t first_replace_len = 0;
-
-  const char* second = "";
-  size_t second_pos = SIZE_MAX;
-  size_t second_replace_len = 0;
-
-  // If we found a %p, then setup our variables accordingly
   if (pid != nullptr) {
-    if (timestamp == nullptr || pid < timestamp) {
+    result_len -= strlen(PidFilenamePlaceholder);
-      first = pid_string;
+    result_len += strlen(pid_string);
-      first_pos = pid - file_name;
-      first_replace_len = strlen(PidFilenamePlaceholder);
-    } else {
-      second = pid_string;
-      second_pos = pid - file_name;
-      second_replace_len = strlen(PidFilenamePlaceholder);
-    }
   }
-
   if (timestamp != nullptr) {
-    if (pid == nullptr || timestamp < pid) {
+    result_len -= strlen(TimestampFilenamePlaceholder);
-      first = timestamp_string;
+    result_len += strlen(timestamp_string);
-      first_pos = timestamp - file_name;
+  }
-      first_replace_len = strlen(TimestampFilenamePlaceholder);
+  if (hostname != nullptr) {
-    } else {
+    if (!os::get_host_name(hostname_string, sizeof(hostname_string))) {
-      second = timestamp_string;
+      int res = jio_snprintf(hostname_string, sizeof(hostname_string), "unknown-host");
-      second_pos = timestamp - file_name;
+      assert(res > 0, "Hostname buffer too small");
-      second_replace_len = strlen(TimestampFilenamePlaceholder);
+    }
-    }
+    result_len -= strlen(HostnameFilenamePlaceholder);
+    result_len += strlen(hostname_string);
   }
-
-  size_t first_len = strlen(first);
-  size_t second_len = strlen(second);
-
   // Allocate the new buffer, size it to hold all we want to put in there +1.
-  size_t result_len =  strlen(file_name) + first_len - first_replace_len + second_len - second_replace_len;
   result = NEW_C_HEAP_ARRAY(char, result_len + 1, mtLogging);
 
   // Assemble the strings
   size_t file_name_pos = 0;
   size_t i = 0;
   while (i < result_len) {
-    if (file_name_pos == first_pos) {
+    if (file_name[file_name_pos] == '%') {
-      // We are in the range of the first placeholder
+      // Replace the first occurrence of any placeholder
-      strcpy(result + i, first);
+      if (pid != nullptr && strncmp(&file_name[file_name_pos],
-      // Bump output buffer position with length of replacing string
+                                    PidFilenamePlaceholder,
-      i += first_len;
+                                    strlen(PidFilenamePlaceholder)) == 0) {
-      // Bump source buffer position to skip placeholder
+        strcpy(result + i, pid_string);
-      file_name_pos += first_replace_len;
+        i += strlen(pid_string);
-    } else if (file_name_pos == second_pos) {
+        file_name_pos += strlen(PidFilenamePlaceholder);
-      // We are in the range of the second placeholder
+        pid = nullptr;
-      strcpy(result + i, second);
+        continue;
-      i += second_len;
+      }
-      file_name_pos += second_replace_len;
+      if (timestamp != nullptr && strncmp(&file_name[file_name_pos],
-    } else {
+                                          TimestampFilenamePlaceholder,
-      // Else, copy char by char of the original file
+                                          strlen(TimestampFilenamePlaceholder)) == 0) {
-      result[i] = file_name[file_name_pos++];
+        strcpy(result + i, timestamp_string);
-      i++;
+        i += strlen(timestamp_string);
+        file_name_pos += strlen(TimestampFilenamePlaceholder);
+        timestamp = nullptr;
+        continue;
+      }
+      if (hostname != nullptr && strncmp(&file_name[file_name_pos],
+                                         HostnameFilenamePlaceholder,
+                                         strlen(HostnameFilenamePlaceholder)) == 0) {
+        strcpy(result + i, hostname_string);
+        i += strlen(hostname_string);
+        file_name_pos += strlen(HostnameFilenamePlaceholder);
+        hostname = nullptr;
+        continue;
+      }
     }
+    // Else, copy char by char of the original file
+    result[i++] = file_name[file_name_pos++];
   }
+  assert(i == result_len, "should be");
+  assert(file_name[file_name_pos] == '\0', "should be");
+
   // Add terminating char
   result[result_len] = '\0';
   return result;

src/hotspot/share/logging/logFileOutput.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -39,10 +39,12 @@ class LogFileOutput : public LogFileStreamOutput {
   static const char* const PidFilenamePlaceholder;
   static const char* const TimestampFilenamePlaceholder;
   static const char* const TimestampFormat;
+  static const char* const HostnameFilenamePlaceholder;
   static const size_t DefaultFileCount = 5;
   static const size_t DefaultFileSize = 20 * M;
   static const size_t StartTimeBufferSize = 20;
   static const size_t PidBufferSize = 21;
+  static const size_t HostnameBufferSize = 512;
   static const uint   MaxRotationFileCount = 1000;
   static char         _pid_str[PidBufferSize];
   static char         _vm_start_time_str[StartTimeBufferSize];

src/java.base/share/man/java.1

@@ -4308,9 +4308,9 @@ The \f[V]-Xlog\f[R] option supports the following types of outputs:
 .IP \[bu] 2
 \f[V]file=\f[R]\f[I]filename\f[R] --- Sends output to text file(s).
 .PP
-When using \f[V]file=\f[R]\f[I]filename\f[R], specifying \f[V]%p\f[R]
+When using \f[V]file=\f[R]\f[I]filename\f[R], specifying \f[V]%p\f[R],
-and/or \f[V]%t\f[R] in the file name expands to the JVM\[aq]s PID and
+\f[V]%t\f[R] and/or \f[V]%hn\f[R] in the file name expands to the
-startup timestamp, respectively.
+JVM\[aq]s PID, startup timestamp and host name, respectively.
 You can also configure text files to handle file rotation based on file
 size and a number of files to rotate.
 For example, to rotate the log file every 10 MB and keep 5 files in