Add prototype for async_metric_source [SMAGENT-1324]

test/userspace/async/async_key_value_source.ut.cpp

@@ -0,0 +1,265 @@
+/*
+Copyright (C) 2018 Sysdig, Inc.
+
+This file is part of sysdig.
+
+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 "async_key_value_source.h"
+
+#include <string>
+#include <gtest.h>
+
+using namespace sysdig;
+
+namespace
+{
+
+/**
+ * Intermediate realization of async_key_value_source that can return pre-canned
+ * results.
+ */
+class precanned_metadata_source : public async_key_value_source<std::string, std::string> 
+{
+public:
+	const static uint64_t FOREVER_MS;
+
+	precanned_metadata_source(const uint64_t max_wait_ms,
+	                          const uint64_t ttl_ms = FOREVER_MS)
+		: async_key_value_source(max_wait_ms, ttl_ms),
+		m_responses()
+	{ }
+
+	void set_response(const std::string& key, const std::string& response)
+	{
+		m_responses[key] = response;
+	}
+
+	std::string get_response(const std::string& key)
+	{
+		return m_responses[key];
+	}
+
+private:
+	std::map<std::string, std::string> m_responses;
+};
+const uint64_t precanned_metadata_source::FOREVER_MS = static_cast<uint64_t>(~0L);
+
+/**
+ * Realization of async_key_value_source that returns results without delay.
+ */
+class immediate_metadata_source : public precanned_metadata_source
+{
+public:
+	const static uint64_t MAX_WAIT_TIME_MS;
+
+	immediate_metadata_source():
+		precanned_metadata_source(MAX_WAIT_TIME_MS)
+	{ }
+
+protected:
+	virtual void run_impl() override
+	{
+		std::string key;
+
+		while(dequeue_next_key(key))
+		{
+			store_value(key, get_response(key));
+		}
+	}
+};
+const uint64_t immediate_metadata_source::MAX_WAIT_TIME_MS = 5000;
+
+/**
+ * Realization of async_key_value_source that returns results with some
+ * specified delay.
+ */
+class delayed_metadata_source : public precanned_metadata_source
+{
+public:
+	const static uint64_t MAX_WAIT_TIME_MS;
+
+	delayed_metadata_source(const uint64_t delay_ms,
+	                        const uint64_t ttl_ms = FOREVER_MS):
+		precanned_metadata_source(MAX_WAIT_TIME_MS, ttl_ms),
+		m_delay_ms(delay_ms)
+	{ }
+
+protected:
+	virtual void run_impl() override
+	{
+		std::string key;
+
+		while(dequeue_next_key(key))
+		{
+			std::this_thread::sleep_for(std::chrono::milliseconds(m_delay_ms));
+			store_value(key, get_response(key));
+		}
+	}
+
+private:
+	uint64_t m_delay_ms;
+};
+const uint64_t delayed_metadata_source::MAX_WAIT_TIME_MS = 0;
+
+}
+
+/**
+ * Ensure that a concrete async_key_value_source is in the expected initial
+ * state after construction.
+ */
+TEST(async_key_value_source_test, construction)
+{
+	immediate_metadata_source source;
+
+	ASSERT_EQ(immediate_metadata_source::MAX_WAIT_TIME_MS, source.get_max_wait());
+	ASSERT_EQ(precanned_metadata_source::FOREVER_MS, source.get_ttl());
+	ASSERT_FALSE(source.is_running());
+}
+
+/**
+ * Ensure that if a concrete async_key_value_source returns the metadata before
+ * the timeout, that the lookup() method returns true, and that it returns
+ * the metadata in the output parameter.
+ */
+TEST(async_key_value_source_test, lookup_key_immediate_return)
+{
+	const std::string key = "foo";
+	const std::string metadata = "bar";
+	std::string response = "response-not-set";
+
+	immediate_metadata_source source;
+
+	// Seed the precanned response
+	source.set_response(key, metadata);
+
+	ASSERT_TRUE(source.lookup(key, response));
+	ASSERT_EQ(metadata, response);
+	ASSERT_TRUE(source.is_running());
+}
+
+/**
+ * Ensure that if a concrete async_key_value_source cannot return the result
+ * before the timeout, and if the client did not provide a callback, that
+ * calling lookup() after the result it available returns the value.
+ */
+TEST(async_key_value_source_test, lookup_key_delayed_return_second_call)
+{
+	const uint64_t DELAY_MS = 50;
+	const std::string key = "mykey";
+	const std::string metadata = "myvalue";
+
+	delayed_metadata_source source(DELAY_MS);
+
+	std::string response = "response-not-set";
+	bool response_found;
+
+	// Seed the precanned response
+	source.set_response(key, metadata);
+
+	response_found = source.lookup(key, response);
+
+	ASSERT_FALSE(response_found);
+
+	// Since we didn't supply a callback, a subsequent call to lookup
+	// after the metadata collection is complete will return the previously
+	// collected metadata.  We know that the delayed_metadata_source is
+	// waiting for DELAY_MS, so wait longer than that.
+	std::this_thread::sleep_for(std::chrono::milliseconds(2 * DELAY_MS));
+
+	// Response should now be available
+	response_found = source.lookup(key, response);
+
+	ASSERT_TRUE(response_found);
+	ASSERT_EQ(metadata, response);
+}
+
+/**
+ * Ensure that if a concrete async_key_value_source cannot return the result
+ * before the timeout, and if the client did provide a callback, that the
+ * callback is invoked with the metadata once they're avaialble.
+ */
+TEST(async_key_value_source_test, look_key_delayed_async_callback)
+{
+	const uint64_t DELAY_MS = 50;
+	const std::string key = "mykey";
+	const std::string metadata = "myvalue";
+
+	delayed_metadata_source source(DELAY_MS);
+
+	std::string sync_response = "sync-response-not-set";
+	std::string async_response = "async-response-not-set";
+	bool response_found;
+
+	// Seed the precanned response
+	source.set_response(key, metadata);
+
+	response_found = source.lookup(key,
+	                               sync_response,
+	                               [&async_response](const std::string& key,
+	                                                 const std::string& value)
+	{
+		async_response = value;
+	});
+
+	ASSERT_FALSE(response_found);
+
+	// Since we supplied a callback, the delayed_metadata_source should
+	// complete after DELAY_MS, and it should immediately call our
+	// callback.  Wait long enough for that to happen.
+	std::this_thread::sleep_for(std::chrono::milliseconds(5 * DELAY_MS));
+
+	ASSERT_EQ(metadata, async_response);
+}
+
+/**
+ * Ensure that "old" results are pruned
+ */
+TEST(async_key_value_source_test, prune_old_metadata)
+{
+	const uint64_t DELAY_MS = 0;
+	const uint64_t TTL_MS = 20;
+
+	const std::string key1 = "mykey1";
+	const std::string metadata1 = "myvalue1";
+
+	const std::string key2 = "mykey2";
+	const std::string metadata2 = "myvalue2";
+
+	delayed_metadata_source source(DELAY_MS, TTL_MS);
+	std::string response = "response-not-set";
+
+	// Seed the precanned response
+	source.set_response(key1, metadata1);
+	source.set_response(key2, metadata2);
+
+	// Since DELAY_MS is 0, then lookup should return false immediately,
+	// and should almost immediately add the result to the cache
+	ASSERT_FALSE(source.lookup(key1, response));
+
+	// Wait long enough for the old entry to require pruning
+	std::this_thread::sleep_for(std::chrono::milliseconds(2 * TTL_MS));
+
+	// Request the other key.  This should wake up the thread and actually
+	// preform the pruning.
+	ASSERT_FALSE(source.lookup(key2, response));
+
+	// Wait long enough for the async thread to get woken up and to
+	// prune the old entry
+	std::this_thread::sleep_for(std::chrono::milliseconds(TTL_MS));
+
+	// Since the first key should have been pruned, a second call to
+	// fetch the first key should also return false.
+	ASSERT_FALSE(source.lookup(key1, response));
+}