changeset 7838:f27530eb6c46

8067447: Factor out the shared implementation of the VM flags manipulation code Reviewed-by: sla, dholmes
author jbachorik
date Tue, 02 Dec 2014 19:47:45 +0100
parents 871f73d10e98
children 4a76ca542247 dba0e5e29ebd
files src/share/vm/services/attachListener.cpp src/share/vm/services/management.cpp src/share/vm/services/writeableFlags.cpp src/share/vm/services/writeableFlags.hpp
diffstat 4 files changed, 349 insertions(+), 192 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/services/attachListener.cpp	Fri Feb 06 10:40:04 2015 -0800
+++ b/src/share/vm/services/attachListener.cpp	Tue Dec 02 19:47:45 2014 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2015, 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
@@ -35,6 +35,7 @@
 #include "runtime/os.hpp"
 #include "services/attachListener.hpp"
 #include "services/diagnosticCommand.hpp"
+#include "services/writeableFlags.hpp"
 #include "services/heapDumper.hpp"
 
 volatile bool AttachListener::_initialized;
@@ -229,133 +230,6 @@
   return JNI_OK;
 }
 
-// set a boolean global flag using value from AttachOperation
-static jint set_bool_flag(const char* name, AttachOperation* op, outputStream* out) {
-  bool value = true;
-  const char* arg1;
-  if ((arg1 = op->arg(1)) != NULL) {
-    int tmp;
-    int n = sscanf(arg1, "%d", &tmp);
-    if (n != 1) {
-      out->print_cr("flag value must be a boolean (1 or 0)");
-      return JNI_ERR;
-    }
-    value = (tmp != 0);
-  }
-  bool res = CommandLineFlags::boolAtPut((char*)name, &value, Flag::ATTACH_ON_DEMAND);
-  if (! res) {
-    out->print_cr("setting flag %s failed", name);
-  }
-  return res? JNI_OK : JNI_ERR;
-}
-
-// set a intx global flag using value from AttachOperation
-static jint set_intx_flag(const char* name, AttachOperation* op, outputStream* out) {
-  intx value;
-  const char* arg1;
-  if ((arg1 = op->arg(1)) != NULL) {
-    int n = sscanf(arg1, INTX_FORMAT, &value);
-    if (n != 1) {
-      out->print_cr("flag value must be an integer");
-      return JNI_ERR;
-    }
-  }
-  bool res = CommandLineFlags::intxAtPut((char*)name, &value, Flag::ATTACH_ON_DEMAND);
-  if (! res) {
-    out->print_cr("setting flag %s failed", name);
-  }
-
-  return res? JNI_OK : JNI_ERR;
-}
-
-// set a uintx global flag using value from AttachOperation
-static jint set_uintx_flag(const char* name, AttachOperation* op, outputStream* out) {
-  uintx value;
-  const char* arg1;
-  if ((arg1 = op->arg(1)) != NULL) {
-    int n = sscanf(arg1, UINTX_FORMAT, &value);
-    if (n != 1) {
-      out->print_cr("flag value must be an unsigned integer");
-      return JNI_ERR;
-    }
-  }
-
-  if (strncmp(name, "MaxHeapFreeRatio", 17) == 0) {
-    FormatBuffer<80> err_msg("%s", "");
-    if (!Arguments::verify_MaxHeapFreeRatio(err_msg, value)) {
-      out->print_cr("%s", err_msg.buffer());
-      return JNI_ERR;
-    }
-  } else if (strncmp(name, "MinHeapFreeRatio", 17) == 0) {
-    FormatBuffer<80> err_msg("%s", "");
-    if (!Arguments::verify_MinHeapFreeRatio(err_msg, value)) {
-      out->print_cr("%s", err_msg.buffer());
-      return JNI_ERR;
-    }
-  }
-  bool res = CommandLineFlags::uintxAtPut((char*)name, &value, Flag::ATTACH_ON_DEMAND);
-  if (! res) {
-    out->print_cr("setting flag %s failed", name);
-  }
-
-  return res? JNI_OK : JNI_ERR;
-}
-
-// set a uint64_t global flag using value from AttachOperation
-static jint set_uint64_t_flag(const char* name, AttachOperation* op, outputStream* out) {
-  uint64_t value;
-  const char* arg1;
-  if ((arg1 = op->arg(1)) != NULL) {
-    int n = sscanf(arg1, UINT64_FORMAT, &value);
-    if (n != 1) {
-      out->print_cr("flag value must be an unsigned 64-bit integer");
-      return JNI_ERR;
-    }
-  }
-  bool res = CommandLineFlags::uint64_tAtPut((char*)name, &value, Flag::ATTACH_ON_DEMAND);
-  if (! res) {
-    out->print_cr("setting flag %s failed", name);
-  }
-
-  return res? JNI_OK : JNI_ERR;
-}
-
-// set a size_t global flag using value from AttachOperation
-static jint set_size_t_flag(const char* name, AttachOperation* op, outputStream* out) {
-  size_t value;
-  const char* arg1;
-  if ((arg1 = op->arg(1)) != NULL) {
-    int n = sscanf(arg1, SIZE_FORMAT, &value);
-    if (n != 1) {
-      out->print_cr("flag value must be an unsigned integer");
-      return JNI_ERR;
-    }
-  }
-  bool res = CommandLineFlags::size_tAtPut((char*)name, &value, Flag::ATTACH_ON_DEMAND);
-  if (! res) {
-    out->print_cr("setting flag %s failed", name);
-  }
-
-  return res? JNI_OK : JNI_ERR;
-}
-
-// set a string global flag using value from AttachOperation
-static jint set_ccstr_flag(const char* name, AttachOperation* op, outputStream* out) {
-  const char* value;
-  if ((value = op->arg(1)) == NULL) {
-    out->print_cr("flag value must be a string");
-    return JNI_ERR;
-  }
-  bool res = CommandLineFlags::ccstrAtPut((char*)name, &value, Flag::ATTACH_ON_DEMAND);
-  if (res) {
-    FREE_C_HEAP_ARRAY(char, value);
-  } else {
-    out->print_cr("setting flag %s failed", name);
-  }
-
-  return res? JNI_OK : JNI_ERR;
-}
-
 // Implementation of "setflag" command
 static jint set_flag(AttachOperation* op, outputStream* out) {
 
@@ -365,27 +239,21 @@
     return JNI_ERR;
   }
 
-  Flag* f = Flag::find_flag((char*)name, strlen(name));
-  if (f && f->is_external() && f->is_writeable()) {
-    if (f->is_bool()) {
-      return set_bool_flag(name, op, out);
-    } else if (f->is_intx()) {
-      return set_intx_flag(name, op, out);
-    } else if (f->is_uintx()) {
-      return set_uintx_flag(name, op, out);
-    } else if (f->is_uint64_t()) {
-      return set_uint64_t_flag(name, op, out);
-    } else if (f->is_size_t()) {
-      return set_size_t_flag(name, op, out);
-    } else if (f->is_ccstr()) {
-      return set_ccstr_flag(name, op, out);
+  FormatBuffer<80> err_msg("%s", "");
+
+  int ret = WriteableFlags::set_flag(op->arg(0), op->arg(1), Flag::ATTACH_ON_DEMAND, err_msg);
+  if (ret != WriteableFlags::SUCCESS) {
+    if (ret == WriteableFlags::NON_WRITABLE) {
+      // if the flag is not manageable try to change it through
+      // the platform dependent implementation
+      return AttachListener::pd_set_flag(op, out);
     } else {
-      ShouldNotReachHere();
-      return JNI_ERR;
+      out->print_cr("%s", err_msg.buffer());
     }
-  } else {
-    return AttachListener::pd_set_flag(op, out);
+
+    return JNI_ERR;
   }
+  return JNI_OK;
 }
 
 // Implementation of "printflag" command
--- a/src/share/vm/services/management.cpp	Fri Feb 06 10:40:04 2015 -0800
+++ b/src/share/vm/services/management.cpp	Tue Dec 02 19:47:45 2014 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2015, 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
@@ -43,6 +43,7 @@
 #include "services/classLoadingService.hpp"
 #include "services/diagnosticCommand.hpp"
 #include "services/diagnosticFramework.hpp"
+#include "services/writeableFlags.hpp"
 #include "services/heapDumper.hpp"
 #include "services/jmm.h"
 #include "services/lowMemoryDetector.hpp"
@@ -1698,56 +1699,21 @@
               "The flag name cannot be null.");
   }
   char* name = java_lang_String::as_utf8_string(fn);
-  Flag* flag = Flag::find_flag(name, strlen(name));
-  if (flag == NULL) {
-    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
-              "Flag does not exist.");
-  }
-  if (!flag->is_writeable()) {
-    THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
-              "This flag is not writeable.");
-  }
 
-  bool succeed = false;
-  if (flag->is_bool()) {
-    bool bvalue = (new_value.z == JNI_TRUE ? true : false);
-    succeed = CommandLineFlags::boolAtPut(name, &bvalue, Flag::MANAGEMENT);
-  } else if (flag->is_intx()) {
-    intx ivalue = (intx)new_value.j;
-    succeed = CommandLineFlags::intxAtPut(name, &ivalue, Flag::MANAGEMENT);
-  } else if (flag->is_uintx()) {
-    uintx uvalue = (uintx)new_value.j;
+  FormatBuffer<80> err_msg("%s", "");
+  int succeed = WriteableFlags::set_flag(name, new_value, Flag::MANAGEMENT, err_msg);
 
-    if (strncmp(name, "MaxHeapFreeRatio", 17) == 0) {
-      FormatBuffer<80> err_msg("%s", "");
-      if (!Arguments::verify_MaxHeapFreeRatio(err_msg, uvalue)) {
-        THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), err_msg.buffer());
-      }
-    } else if (strncmp(name, "MinHeapFreeRatio", 17) == 0) {
-      FormatBuffer<80> err_msg("%s", "");
-      if (!Arguments::verify_MinHeapFreeRatio(err_msg, uvalue)) {
-        THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), err_msg.buffer());
-      }
-    }
-    succeed = CommandLineFlags::uintxAtPut(name, &uvalue, Flag::MANAGEMENT);
-  } else if (flag->is_uint64_t()) {
-    uint64_t uvalue = (uint64_t)new_value.j;
-    succeed = CommandLineFlags::uint64_tAtPut(name, &uvalue, Flag::MANAGEMENT);
-  } else if (flag->is_size_t()) {
-    size_t svalue = (size_t)new_value.j;
-    succeed = CommandLineFlags::size_tAtPut(name, &svalue, Flag::MANAGEMENT);
-  } else if (flag->is_ccstr()) {
-    oop str = JNIHandles::resolve_external_guard(new_value.l);
-    if (str == NULL) {
+  if (succeed != WriteableFlags::SUCCESS) {
+    if (succeed == WriteableFlags::MISSING_VALUE) {
+      // missing value causes NPE to be thrown
       THROW(vmSymbols::java_lang_NullPointerException());
-    }
-    ccstr svalue = java_lang_String::as_utf8_string(str);
-    succeed = CommandLineFlags::ccstrAtPut(name, &svalue, Flag::MANAGEMENT);
-    if (succeed) {
-      FREE_C_HEAP_ARRAY(char, svalue);
+    } else {
+      // all the other errors are reported as IAE with the appropriate error message
+      THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
+                err_msg.buffer());
     }
   }
-  assert(succeed, "Setting flag should succeed");
+  assert(succeed == WriteableFlags::SUCCESS, "Setting flag should succeed");
 JVM_END
 
 class ThreadTimesClosure: public ThreadClosure {
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/services/writeableFlags.cpp	Tue Dec 02 19:47:45 2014 +0100
@@ -0,0 +1,226 @@
+/*
+ * Copyright (c) 2015, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/javaClasses.hpp"
+#include "runtime/arguments.hpp"
+#include "runtime/java.hpp"
+#include "runtime/jniHandles.hpp"
+#include "services/writeableFlags.hpp"
+
+// set a boolean global flag
+int WriteableFlags::set_bool_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  int value = true;
+
+  if (sscanf(arg, "%d", &value)) {
+    return set_bool_flag(name, value != 0, origin, err_msg);
+  }
+  err_msg.print("flag value must be a boolean (1 or 0)");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_bool_flag(const char* name, bool value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return CommandLineFlags::boolAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a intx global flag
+int WriteableFlags::set_intx_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  intx value;
+
+  if (sscanf(arg, INTX_FORMAT, &value)) {
+    return set_intx_flag(name, value, origin, err_msg);
+  }
+  err_msg.print("flag value must be an integer");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_intx_flag(const char* name, intx value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return CommandLineFlags::intxAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a uintx global flag
+int WriteableFlags::set_uintx_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  uintx value;
+
+  if (sscanf(arg, UINTX_FORMAT, &value)) {
+    return set_uintx_flag(name, value, origin, err_msg);
+  }
+  err_msg.print("flag value must be an unsigned integer");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_uintx_flag(const char* name, uintx value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  if (strncmp(name, "MaxHeapFreeRatio", 17) == 0) {
+      if (!Arguments::verify_MaxHeapFreeRatio(err_msg, value)) {
+        return OUT_OF_BOUNDS;
+      }
+    } else if (strncmp(name, "MinHeapFreeRatio", 17) == 0) {
+      if (!Arguments::verify_MinHeapFreeRatio(err_msg, value)) {
+        return OUT_OF_BOUNDS;
+      }
+    }
+    return CommandLineFlags::uintxAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a uint64_t global flag
+int WriteableFlags::set_uint64_t_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  uint64_t value;
+
+  if (sscanf(arg, UINT64_FORMAT, &value)) {
+    return set_uint64_t_flag(name, value, origin, err_msg);
+  }
+  err_msg.print("flag value must be an unsigned 64-bit integer");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_uint64_t_flag(const char* name, uint64_t value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return CommandLineFlags::uint64_tAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a size_t global flag
+int WriteableFlags::set_size_t_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  size_t value;
+
+  if (sscanf(arg, SIZE_FORMAT, &value)) {
+    return set_size_t_flag(name, value, origin, err_msg);
+  }
+  err_msg.print("flag value must be an unsigned integer");
+  return WRONG_FORMAT;
+}
+
+int WriteableFlags::set_size_t_flag(const char* name, size_t value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return CommandLineFlags::size_tAtPut((char*)name, &value, origin) ? SUCCESS : ERR_OTHER;
+}
+
+// set a string global flag using value from AttachOperation
+int WriteableFlags::set_ccstr_flag(const char* name, const char* arg, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  bool res = CommandLineFlags::ccstrAtPut((char*)name, &arg, origin);
+
+  return res? SUCCESS : ERR_OTHER;
+}
+
+/* sets a writeable flag to the provided value
+ *
+ * - return status is one of the WriteableFlags::err enum values
+ * - an eventual error message will be generated to the provided err_msg buffer
+ */
+int WriteableFlags::set_flag(const char* flag_name, const char* flag_value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return set_flag(flag_name, &flag_value, set_flag_from_char, origin, err_msg);
+}
+
+/* sets a writeable flag to the provided value
+ *
+ * - return status is one of the WriteableFlags::err enum values
+ * - an eventual error message will be generated to the provided err_msg buffer
+ */
+int WriteableFlags::set_flag(const char* flag_name, jvalue flag_value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  return set_flag(flag_name, &flag_value, set_flag_from_jvalue, origin, err_msg);
+}
+
+// a writeable flag setter accepting either 'jvalue' or 'char *' values
+int WriteableFlags::set_flag(const char* name, const void* value, int(*setter)(Flag*,const void*,Flag::Flags,FormatBuffer<80>&), Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  if (name == NULL) {
+    err_msg.print("flag name is missing");
+    return MISSING_NAME;
+  }
+  if (value == NULL) {
+    err_msg.print("flag value is missing");
+    return MISSING_VALUE;
+  }
+
+  Flag* f = Flag::find_flag((char*)name, strlen(name));
+  if (f) {
+    // only writeable flags are allowed to be set
+    if (f->is_writeable()) {
+      return setter(f, value, origin, err_msg);
+    } else {
+      err_msg.print("only 'writeable' flags can be set");
+      return NON_WRITABLE;
+    }
+  }
+
+  err_msg.print("flag %s does not exist", name);
+  return INVALID_FLAG;
+}
+
+// a writeable flag setter accepting 'char *' values
+int WriteableFlags::set_flag_from_char(Flag* f, const void* value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  char* flag_value = *(char**)value;
+  if (flag_value == NULL) {
+    err_msg.print("flag value is missing");
+    return MISSING_VALUE;
+  }
+  if (f->is_bool()) {
+    return set_bool_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_intx()) {
+    return set_intx_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_uintx()) {
+    return set_uintx_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_uint64_t()) {
+    return set_uint64_t_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_size_t()) {
+    return set_size_t_flag(f->_name, flag_value, origin, err_msg);
+  } else if (f->is_ccstr()) {
+    return set_ccstr_flag(f->_name, flag_value, origin, err_msg);
+  } else {
+    ShouldNotReachHere();
+  }
+  return ERR_OTHER;
+}
+
+// a writeable flag setter accepting 'jvalue' values
+int WriteableFlags::set_flag_from_jvalue(Flag* f, const void* value, Flag::Flags origin, FormatBuffer<80>& err_msg) {
+  jvalue new_value = *(jvalue*)value;
+  if (f->is_bool()) {
+    bool bvalue = (new_value.z == JNI_TRUE ? true : false);
+    return set_bool_flag(f->_name, bvalue, origin, err_msg);
+  } else if (f->is_intx()) {
+    intx ivalue = (intx)new_value.j;
+    return set_intx_flag(f->_name, ivalue, origin, err_msg);
+  } else if (f->is_uintx()) {
+    uintx uvalue = (uintx)new_value.j;
+    return set_uintx_flag(f->_name, uvalue, origin, err_msg);
+  } else if (f->is_uint64_t()) {
+    uint64_t uvalue = (uint64_t)new_value.j;
+    return set_uint64_t_flag(f->_name, uvalue, origin, err_msg);
+  } else if (f->is_size_t()) {
+    size_t svalue = (size_t)new_value.j;
+    return set_size_t_flag(f->_name, svalue, origin, err_msg);
+  } else if (f->is_ccstr()) {
+    oop str = JNIHandles::resolve_external_guard(new_value.l);
+    if (str == NULL) {
+      err_msg.print("flag value is missing");
+      return MISSING_VALUE;
+    }
+    ccstr svalue = java_lang_String::as_utf8_string(str);
+    int ret = WriteableFlags::set_ccstr_flag(f->_name, svalue, origin, err_msg);
+    if (ret != SUCCESS) {
+      FREE_C_HEAP_ARRAY(char, svalue);
+    }
+    return ret;
+  } else {
+    ShouldNotReachHere();
+  }
+  return ERR_OTHER;
+}
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/services/writeableFlags.hpp	Tue Dec 02 19:47:45 2014 +0100
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2015, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_SERVICES_WRITEABLEFLAG_HPP
+#define SHARE_VM_SERVICES_WRITEABLEFLAG_HPP
+
+class WriteableFlags : AllStatic {
+public:
+  enum error {
+    // no error
+    SUCCESS,
+    // flag name is missing
+    MISSING_NAME,
+    // flag value is missing
+    MISSING_VALUE,
+    // error parsing the textual form of the value
+    WRONG_FORMAT,
+    // flag is not writeable
+    NON_WRITABLE,
+    // flag value is outside of its bounds
+    OUT_OF_BOUNDS,
+    // there is no flag with the given name
+    INVALID_FLAG,
+    // other, unspecified error related to setting the flag
+    ERR_OTHER
+  } err;
+
+private:
+  // a writeable flag setter accepting either 'jvalue' or 'char *' values
+  static int set_flag(const char* name, const void* value, int(*setter)(Flag*, const void*, Flag::Flags, FormatBuffer<80>&), Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // a writeable flag setter accepting 'char *' values
+  static int set_flag_from_char(Flag* f, const void* value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // a writeable flag setter accepting 'jvalue' values
+  static int set_flag_from_jvalue(Flag* f, const void* value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+
+  // set a boolean global flag
+  static int set_bool_flag(const char* name, const char* value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a intx global flag
+  static int set_intx_flag(const char* name, const char* value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a uintx global flag
+  static int set_uintx_flag(const char* name, const char* value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a uint64_t global flag
+  static int set_uint64_t_flag(const char* name, const char* value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a size_t global flag using value from AttachOperation
+  static int set_size_t_flag(const char* name, const char* value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a boolean global flag
+  static int set_bool_flag(const char* name, bool value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a intx global flag
+  static int set_intx_flag(const char* name, intx value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a uintx global flag
+  static int set_uintx_flag(const char* name, uintx value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a uint64_t global flag
+  static int set_uint64_t_flag(const char* name, uint64_t value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a size_t global flag using value from AttachOperation
+  static int set_size_t_flag(const char* name, size_t value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+  // set a string global flag
+  static int set_ccstr_flag(const char* name, const char* value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+
+public:
+  /* sets a writeable flag to the provided value
+   *
+   * - return status is one of the WriteableFlags::err enum values
+   * - an eventual error message will be generated to the provided err_msg buffer
+   */
+  static int set_flag(const char* flag_name, const char* flag_value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+
+  /* sets a writeable flag to the provided value
+   *
+   * - return status is one of the WriteableFlags::err enum values
+   * - an eventual error message will be generated to the provided err_msg buffer
+   */
+  static int set_flag(const char* flag_name, jvalue flag_value, Flag::Flags origin, FormatBuffer<80>& err_msg);
+};
+
+#endif /* SHARE_VM_SERVICES_WRITEABLEFLAG_HPP */
+