SERVER-9809 Introduce mongo-wide ProcessId type.

4 files changed, 222 insertions, 2 deletions

diff --git a/src/mongo/platform/SConscript b/src/mongo/platform/SConscript
index c18fbae3ce8..66aad9a87cb 100644
--- a/src/mongo/platform/SConscript
+++ b/src/mongo/platform/SConscript
@@ -2,8 +2,12 @@
 
 Import("env")
 
-env.Library( "platform", "random.cpp" )
+env.Library('platform', [
+        'process_id.cpp',
+        'random.cpp',
+        ])
 
 env.CppUnitTest('atomic_word_test', 'atomic_word_test.cpp')
 env.CppUnitTest('bits_test', 'bits_test.cpp')
-env.CppUnitTest('random_test', 'random_test.cpp')
+env.CppUnitTest('process_id_test', 'process_id_test.cpp', LIBDEPS=['platform'])
+env.CppUnitTest('random_test', 'random_test.cpp', LIBDEPS=['platform'])
diff --git a/src/mongo/platform/process_id.cpp b/src/mongo/platform/process_id.cpp
new file mode 100644
index 00000000000..ef5a6ecc80b
--- /dev/null
+++ b/src/mongo/platform/process_id.cpp
@@ -0,0 +1,56 @@
+/*    Copyright 2013 10gen Inc.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/platform/process_id.h"
+
+#include <boost/static_assert.hpp>
+#include <iostream>
+#include <limits>
+
+namespace mongo {
+
+    BOOST_STATIC_ASSERT(sizeof(NativeProcessId) == sizeof(uint32_t));
+
+    namespace {
+#ifdef _WIN32
+        inline NativeProcessId getCurrentNativeProcessId() { return GetCurrentProcessId(); }
+#else
+        inline NativeProcessId getCurrentNativeProcessId() { return getpid(); }
+#endif
+    }  // namespace
+
+    ProcessId ProcessId::getCurrent() {
+        return fromNative(getCurrentNativeProcessId());
+    }
+
+    int64_t ProcessId::asInt64() const {
+        typedef std::numeric_limits<NativeProcessId> limits;
+        if (limits::is_signed)
+            return _npid;
+        else
+            return static_cast<int64_t>(static_cast<uint64_t>(_npid));
+    }
+
+    long long ProcessId::asLongLong() const {
+        return static_cast<long long>(asInt64());
+    }
+
+    std::ostream& operator<<(std::ostream& os, ProcessId pid) {
+        return os << pid.asInt64();
+    }
+
+}  // namespace mongo
diff --git a/src/mongo/platform/process_id.h b/src/mongo/platform/process_id.h
new file mode 100644
index 00000000000..208b921a1c0
--- /dev/null
+++ b/src/mongo/platform/process_id.h
@@ -0,0 +1,106 @@
+/*    Copyright 2013 10gen Inc.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#pragma once
+
+#include <iosfwd>
+
+#ifndef _WIN32
+#include <unistd.h>
+#endif
+
+#include "mongo/platform/cstdint.h"
+#include "mongo/platform/hash_namespace.h"
+
+namespace mongo {
+
+#ifdef _WIN32
+    typedef DWORD NativeProcessId;
+#else
+    typedef pid_t NativeProcessId;
+#endif
+
+    /**
+     * Platform-independent representation of a process identifier.
+     */
+    class ProcessId {
+    public:
+        /**
+         * Gets the process id for the currently executing process.
+         */
+        static ProcessId getCurrent();
+
+        /**
+         * Constructs a ProcessId from a NativeProcessId.
+         */
+        static inline ProcessId fromNative(NativeProcessId npid) { return ProcessId(npid); }
+
+        /**
+         * Constructs a ProcessId with an unspecified value.
+         */
+        ProcessId() {}
+
+        /**
+         * Gets the native process id corresponding to this ProcessId.
+         */
+        NativeProcessId toNative() const { return _npid; }
+
+        /**
+         * Represents this process id as a signed 64-bit integer.
+         *
+         * This representation will faithfully serialize and format to text files, but is at least
+         * twice the number of bits needed to uniquely represent valid process numbers on supported
+         * OSes..
+         */
+        int64_t asInt64() const;
+
+        /**
+         * Similar to asInt64(), for compatibility with code that uses "long long" to mean 64-bit
+         * signed integer.
+         */
+        long long asLongLong() const;
+
+        /**
+         * Represents this process id as an unsigned 32-bit integer.
+         *
+         * This representation will contain all of the bits of the native process id, but may not
+         * serialize or format to text files meaningfully.
+         */
+        uint32_t asUInt32() const { return static_cast<uint32_t>(_npid); }
+
+        bool operator==(const ProcessId other) const { return _npid == other._npid; }
+        bool operator!=(const ProcessId other) const { return _npid != other._npid; }
+        bool operator<(const ProcessId other) const { return _npid < other._npid; }
+        bool operator<=(const ProcessId other) const { return _npid <= other._npid; }
+        bool operator>(const ProcessId other) const { return _npid > other._npid; }
+        bool operator>=(const ProcessId other) const { return _npid >= other._npid; }
+
+    private:
+        explicit ProcessId(NativeProcessId npid): _npid(npid) {}
+
+        NativeProcessId _npid;
+    };
+
+    std::ostream& operator<<(std::ostream& os, ProcessId pid);
+
+}  // namespace mongo
+
+MONGO_HASH_NAMESPACE_START
+template<> struct hash< ::mongo::ProcessId > {
+    size_t operator()(const ::mongo::ProcessId pid) const {
+        return hash< ::mongo::uint32_t >()(pid.asUInt32());
+    }
+};
+MONGO_HASH_NAMESPACE_END
diff --git a/src/mongo/platform/process_id_test.cpp b/src/mongo/platform/process_id_test.cpp
new file mode 100644
index 00000000000..83053e3d886
--- /dev/null
+++ b/src/mongo/platform/process_id_test.cpp
@@ -0,0 +1,54 @@
+/*    Copyright 2013 10gen Inc.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#include "mongo/platform/process_id.h"
+#include "mongo/unittest/unittest.h"
+
+namespace mongo {
+namespace {
+
+    TEST(ProcessId, Comparison) {
+        const ProcessId p1 = ProcessId::fromNative(NativeProcessId(1));
+        const ProcessId p2 = ProcessId::fromNative(NativeProcessId(2));
+
+        ASSERT_FALSE(p1 == p2);
+        ASSERT_TRUE(p1 == p1);
+
+        ASSERT_TRUE(p1 != p2);
+        ASSERT_FALSE(p1 != p1);
+
+        ASSERT_TRUE(p1 < p2);
+        ASSERT_FALSE(p1 < p1);
+        ASSERT_FALSE(p2 < p1);
+
+        ASSERT_TRUE(p1 <= p2);
+        ASSERT_TRUE(p1 <= p1);
+        ASSERT_FALSE(p2 <= p1);
+
+        ASSERT_TRUE(p2 > p1);
+        ASSERT_FALSE(p2 > p2);
+        ASSERT_FALSE(p1 > p2);
+
+        ASSERT_TRUE(p2 >= p1);
+        ASSERT_TRUE(p2 >= p2);
+        ASSERT_FALSE(p1 >= p2);
+    }
+
+    TEST(ProcessId, GetCurrentEqualsSelf) {
+        ASSERT_EQUALS(ProcessId::getCurrent(), ProcessId::getCurrent());
+    }
+
+}  // namespace
+}  // namespace mongo