SERVER-5112 Initializer type and test.

7 files changed, 368 insertions, 0 deletions

diff --git a/src/mongo/base/SConscript b/src/mongo/base/SConscript
index 6bc1aa8a7cb..0c7d29abe9b 100644
--- a/src/mongo/base/SConscript
+++ b/src/mongo/base/SConscript
@@ -3,6 +3,8 @@
 Import("env")
 
 env.StaticLibrary('base', ['configuration_variable_manager.cpp',
+                           'initializer.cpp',
+                           'initializer_context.cpp',
                            'initializer_dependency_graph.cpp',
                            'make_string_vector.cpp',
                            'parse_number.cpp',
@@ -24,3 +26,5 @@ env.CppUnitTest('configuration_variable_manager_test',
 
 env.CppUnitTest('parse_number_test', ['parse_number_test.cpp'], LIBDEPS=['base'])
 
+env.CppUnitTest('initializer_test', ['initializer_test.cpp'], LIBDEPS=['base'])
+
diff --git a/src/mongo/base/error_codes.h b/src/mongo/base/error_codes.h
index 0cc9dfafdf2..3c53e8b8080 100644
--- a/src/mongo/base/error_codes.h
+++ b/src/mongo/base/error_codes.h
@@ -49,6 +49,7 @@ namespace mongo {
             GraphContainsCycle = 5,
             HostUnreachable = 6,
             HostNotFound = 7,
+            UnknownError = 8,
             FailedToParse = 9,
             MaxError
         };
@@ -71,6 +72,8 @@ namespace mongo {
                 return "DuplicateKey";
             case GraphContainsCycle:
                 return "GraphContainsCycle";
+            case UnknownError:
+                return "UnknownError";
             case FailedToParse:
                 return "FailedToParse";
             default:
diff --git a/src/mongo/base/initializer.cpp b/src/mongo/base/initializer.cpp
new file mode 100644
index 00000000000..f1921ba5637
--- /dev/null
+++ b/src/mongo/base/initializer.cpp
@@ -0,0 +1,47 @@
+/*    Copyright 2012 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/base/initializer.h"
+
+namespace mongo {
+
+    Initializer::Initializer() {}
+    Initializer::~Initializer() {}
+
+    Status Initializer::execute(const InitializerContext::ArgumentVector& args,
+                                const InitializerContext::EnvironmentMap& env) const {
+
+        std::vector<std::string> sortedNodes;
+        Status status = _graph.topSort(&sortedNodes);
+        if (Status::OK() != status)
+            return status;
+
+        InitializerContext context(args, env, &_configVariables);
+
+        for (size_t i = 0; i < sortedNodes.size(); ++i) {
+            InitializerFunction fn = _graph.getInitializerFunction(sortedNodes[i]);
+            if (!fn) {
+                return Status(ErrorCodes::InternalError,
+                              "topSort returned a node that has no associated function: \"" +
+                              sortedNodes[i] + '"');
+            }
+            status = fn(&context);
+            if (Status::OK() != status)
+                return status;
+        }
+        return Status::OK();
+    }
+
+}  // namespace mongo
diff --git a/src/mongo/base/initializer.h b/src/mongo/base/initializer.h
new file mode 100644
index 00000000000..7d03cd6e40c
--- /dev/null
+++ b/src/mongo/base/initializer.h
@@ -0,0 +1,71 @@
+/*    Copyright 2012 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 <string>
+#include <vector>
+
+#include "mongo/base/configuration_variable_manager.h"
+#include "mongo/base/disallow_copying.h"
+#include "mongo/base/initializer_context.h"
+#include "mongo/base/initializer_dependency_graph.h"
+#include "mongo/base/status.h"
+
+namespace mongo {
+
+    /**
+     * Class representing an initialization process.
+     *
+     * Such a process is described by a directed acyclic graph of initialization operations, the
+     * InitializerDependencyGraph, and a collection of mutable global state, the
+     * ConfigurationVariableManager.  One constructs an initialization process by adding nodes and
+     * edges to the graph, and variable mappings in the variable manager.  Then, one executes the
+     * process, causing each initialization operation to execute in an order that respects the
+     * programmer-established prerequistes.
+     */
+    class Initializer {
+        MONGO_DISALLOW_COPYING(Initializer);
+    public:
+        Initializer();
+        ~Initializer();
+
+        /**
+         * Get the initializer dependency graph, presumably for the purpose of adding more nodes.
+         */
+        InitializerDependencyGraph& getInitializerDependencyGraph() { return _graph; }
+
+        /**
+         * Get the configuration variable manager, for the purpose of describing more configurable
+         * variables.
+         */
+        ConfigurationVariableManager& getConfigurationVariableManager() { return _configVariables; }
+
+        /**
+         * Execute the initializer process, using the given argv and environment data as input.
+         *
+         * Returns Status::OK on success.  All other returns constitute initialization failures,
+         * and the thing being initialized should be considered dead in the water.
+         */
+        Status execute(const InitializerContext::ArgumentVector& args,
+                       const InitializerContext::EnvironmentMap& env) const;
+
+    private:
+
+        InitializerDependencyGraph _graph;
+        ConfigurationVariableManager _configVariables;
+    };
+
+}  // namespace mongo
diff --git a/src/mongo/base/initializer_context.cpp b/src/mongo/base/initializer_context.cpp
new file mode 100644
index 00000000000..9c2e54caf3f
--- /dev/null
+++ b/src/mongo/base/initializer_context.cpp
@@ -0,0 +1,25 @@
+/*    Copyright 2012 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/base/initializer_context.h"
+
+namespace mongo {
+
+    InitializerContext::InitializerContext(const ArgumentVector& args,
+                                           const EnvironmentMap& env,
+                                           const ConfigurationVariableManager* configVariables)
+        : _args(args), _env(env), _configVariables(configVariables) {}
+
+}  // namespace mongo
diff --git a/src/mongo/base/initializer_context.h b/src/mongo/base/initializer_context.h
new file mode 100644
index 00000000000..915e18f600e
--- /dev/null
+++ b/src/mongo/base/initializer_context.h
@@ -0,0 +1,53 @@
+/*    Copyright 2012 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 <map>
+#include <string>
+#include <vector>
+
+#include "mongo/base/configuration_variable_manager.h"
+#include "mongo/base/disallow_copying.h"
+
+namespace mongo {
+
+    /**
+     * Context of an initialization process.  Passed as a parameter to initialization functions.
+     *
+     * See mongo/base/initializer.h and mongo/base/initializer_dependency_graph.h for more details.
+     */
+    class InitializerContext {
+        MONGO_DISALLOW_COPYING(InitializerContext);
+
+    public:
+        typedef std::vector<std::string> ArgumentVector;
+        typedef std::map<std::string, std::string> EnvironmentMap;
+
+        InitializerContext(const ArgumentVector& args,
+                           const EnvironmentMap& env,
+                           const ConfigurationVariableManager* configVariables);
+
+        const ArgumentVector& args() const { return _args; }
+        const EnvironmentMap& env() const { return _env; }
+        const ConfigurationVariableManager* configurationVariables() { return _configVariables; }
+
+    private:
+        ArgumentVector _args;
+        EnvironmentMap _env;
+        const ConfigurationVariableManager* _configVariables;
+    };
+
+}  // namespace mongo
diff --git a/src/mongo/base/initializer_test.cpp b/src/mongo/base/initializer_test.cpp
new file mode 100644
index 00000000000..88824f15ba8
--- /dev/null
+++ b/src/mongo/base/initializer_test.cpp
@@ -0,0 +1,165 @@
+/*    Copyright 2012 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.
+ */
+
+/**
+ * Unit tests of the Initializer type.
+ */
+
+#include "mongo/base/initializer.h"
+#include "mongo/base/initializer_dependency_graph.h"
+#include "mongo/base/make_string_vector.h"
+#include "mongo/unittest/unittest.h"
+
+/*
+ * Unless otherwise specified, all tests herein use the following
+ * dependency graph.
+ *
+ * 0 <-  3 <- 7
+ *  ^   / ^    ^
+ *   \ v   \     \ 
+ *    2     5 <-  8
+ *   / ^   /     /
+ *  v   \ v    v
+ * 1 <-  4 <- 6
+ *
+ */
+
+#define ADD_INITIALIZER(GRAPH, NAME, FN, PREREQS, DEPS)                 \
+    (GRAPH).addInitializer(                                             \
+            (NAME),                                                     \
+            (FN),                                                       \
+            MONGO_MAKE_STRING_VECTOR PREREQS,                           \
+            MONGO_MAKE_STRING_VECTOR DEPS)
+
+#define ASSERT_OK(EXPR) ASSERT_EQUALS(Status::OK(), EXPR)
+
+#define ASSERT_ADD_INITIALIZER(GRAPH, NAME, FN, PREREQS, DEPS)  \
+    ASSERT_EQUALS(Status::OK(), ADD_INITIALIZER(GRAPH, NAME, FN, PREREQS, DEPS))
+
+
+#define CONSTRUCT_DEPENDENCY_GRAPH(GRAPH, FN0, FN1, FN2, FN3, FN4, FN5, FN6, FN7, FN8) \
+    do {                                                                \
+        InitializerDependencyGraph& _graph_ = (GRAPH);                  \
+        ASSERT_ADD_INITIALIZER(_graph_, "n0", FN0, (), ());             \
+        ASSERT_ADD_INITIALIZER(_graph_, "n1", FN1, (), ());             \
+        ASSERT_ADD_INITIALIZER(_graph_, "n2", FN2, ("n0", "n1"), ());   \
+        ASSERT_ADD_INITIALIZER(_graph_, "n3", FN3, ("n0", "n2"), ());   \
+        ASSERT_ADD_INITIALIZER(_graph_, "n4", FN4, ("n2", "n1"), ());   \
+        ASSERT_ADD_INITIALIZER(_graph_, "n5", FN5, ("n3", "n4"), ());   \
+        ASSERT_ADD_INITIALIZER(_graph_, "n6", FN6, ("n4"), ());         \
+        ASSERT_ADD_INITIALIZER(_graph_, "n7", FN7, ("n3"), ());         \
+        ASSERT_ADD_INITIALIZER(_graph_, "n8", FN8, ("n5", "n6", "n7"), ()); \
+    } while (false)
+
+namespace mongo {
+namespace {
+
+    int globalCounts[9];
+
+    Status doNothing(InitializerContext*) { return Status::OK(); }
+
+    Status set0(InitializerContext*) {
+        globalCounts[0] = 1;
+        return Status::OK();
+    }
+
+    Status set1(InitializerContext*) {
+        globalCounts[1] = 1;
+        return Status::OK();
+    }
+
+    Status set2(InitializerContext*) {
+        if (!globalCounts[0] || !globalCounts[1])
+            return Status(ErrorCodes::UnknownError, "one of 0 or 1 not already set");
+        globalCounts[2] = 1;
+        return Status::OK();
+    }
+
+    Status set3(InitializerContext*) {
+        if (!globalCounts[0] || !globalCounts[2])
+            return Status(ErrorCodes::UnknownError, "one of 0 or 2 not already set");
+        globalCounts[3] = 1;
+        return Status::OK();
+    }
+
+    Status set4(InitializerContext*) {
+        if (!globalCounts[1] || !globalCounts[2])
+            return Status(ErrorCodes::UnknownError, "one of 1 or 2 not already set");
+        globalCounts[4] = 1;
+        return Status::OK();
+    }
+
+    Status set5(InitializerContext*) {
+        if (!globalCounts[3] || !globalCounts[4])
+            return Status(ErrorCodes::UnknownError, "one of 3 or 4 not already set");
+        globalCounts[5] = 1;
+        return Status::OK();
+    }
+
+    Status set6(InitializerContext*) {
+        if (!globalCounts[4])
+            return Status(ErrorCodes::UnknownError, "4 not already set");
+        globalCounts[6] = 1;
+        return Status::OK();
+    }
+
+    Status set7(InitializerContext*) {
+        if (!globalCounts[3])
+            return Status(ErrorCodes::UnknownError, "3 not already set");
+        globalCounts[7] = 1;
+        return Status::OK();
+    }
+
+    Status set8(InitializerContext*) {
+        if (!globalCounts[5] || !globalCounts[6] || !globalCounts[7])
+            return Status(ErrorCodes::UnknownError, "one of 5, 6, 7 not already set");
+        globalCounts[8] = 1;
+        return Status::OK();
+    }
+
+    void clearCounts() {
+        for (size_t i = 0; i < 9; ++i)
+            globalCounts[i] = 0;
+    }
+
+    TEST(InitializerTest, SuccessfulInitialization) {
+        Initializer initializer;
+        CONSTRUCT_DEPENDENCY_GRAPH(initializer.getInitializerDependencyGraph(),
+                                   set0, set1, set2, set3, set4, set5, set6, set7, set8);
+        clearCounts();
+        ASSERT_OK(initializer.execute(InitializerContext::ArgumentVector(),
+                                      InitializerContext::EnvironmentMap()));
+        for (int i = 0; i < 9; ++i)
+            ASSERT_EQUALS(1, globalCounts[i]);
+    }
+
+    TEST(InitializerTest, Step5Misimplemented) {
+        Initializer initializer;
+        CONSTRUCT_DEPENDENCY_GRAPH(initializer.getInitializerDependencyGraph(),
+                                   set0, set1, set2, set3, set4, doNothing, set6, set7, set8);
+        clearCounts();
+        ASSERT_EQUALS(ErrorCodes::UnknownError,
+                      initializer.execute(InitializerContext::ArgumentVector(),
+                                          InitializerContext::EnvironmentMap()));
+        ASSERT_EQUALS(1, globalCounts[0]);
+        ASSERT_EQUALS(1, globalCounts[1]);
+        ASSERT_EQUALS(1, globalCounts[2]);
+        ASSERT_EQUALS(1, globalCounts[3]);
+        ASSERT_EQUALS(1, globalCounts[4]);
+        ASSERT_EQUALS(0, globalCounts[8]);
+    }
+
+}  // namespace
+}  // namespace mongo