Add initial zookeeper wrapper code

src/CMakeLists.txt

@@ -15,4 +15,12 @@ set(SOURCES
     consumer.cpp
 )
 
+if (ENABLE_ZOOKEEPER)
+    set(ZOOKEEPER_SOURCES
+        ${CMAKE_CURRENT_SOURCE_DIR}/zookeeper/zookeeper_watcher.cpp)
+    # Add json library as include dir (header only)
+    include_directories(SYSTEM ${CMAKE_CURRENT_SOURCE_DIR}/../third_party/json)
+    set(SOURCES ${SOURCES} ${ZOOKEEPER_SOURCES})
+endif()
+
 add_library(cppkafka ${SOURCES})

src/zookeeper/zookeeper_watcher.cpp

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2016, Matias Fontanini
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following disclaimer
+ *   in the documentation and/or other materials provided with the
+ *   distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <stdexcept>
+#include <sstream>
+#include <picojson.h>
+#include "zookeeper/zookeeper_watcher.h"
+#include "exceptions.h"
+
+using std::string;
+using std::unique_ptr;
+using std::ostringstream;
+using std::runtime_error;
+using std::chrono::milliseconds;
+
+using picojson::value;
+using picojson::object;
+
+namespace cppkafka {
+
+const milliseconds ZookeeperWatcher::DEFAULT_RECEIVE_TIMEOUT{10000};
+const string ZookeeperWatcher::BROKERS_PATH = "/brokers/ids";
+
+ZookeeperWatcher::ZookeeperWatcher(const string& endpoint)
+: ZookeeperWatcher(endpoint, DEFAULT_RECEIVE_TIMEOUT) {
+
+}
+
+ZookeeperWatcher::ZookeeperWatcher(const string& endpoint, milliseconds receive_timeout)
+: handle_(nullptr, nullptr) {
+    auto raw_handle = zookeeper_init(endpoint.data(), &ZookeeperWatcher::handle_event_proxy,
+                                     receive_timeout.count(), nullptr, this, 0);
+    if (!raw_handle) {
+        // TODO: make this a proper exception
+        throw runtime_error("Failed to create zookeeper handle");
+    }
+    handle_ = HandlePtr(raw_handle, &zookeeper_close);
+}
+
+string ZookeeperWatcher::get_brokers() {
+    using VectorPtr = unique_ptr<String_vector, decltype(&deallocate_String_vector)>;
+    String_vector brokers;
+    if (zoo_get_children(handle_.get(), BROKERS_PATH.data(), 1, &brokers) != ZOK) {
+        throw ZookeeperException("Failed to get broker list from zookeeper");
+    }
+    // RAII up this pointer
+    ostringstream oss;
+    VectorPtr _(&brokers, &deallocate_String_vector);
+    for (int i = 0; i < brokers.count; i++) {
+        char config_line[1024];
+        string path = "/brokers/ids/" + string(brokers.data[i]);
+        int config_len = sizeof(config_line);
+        zoo_get(handle_.get(), path.data(), 0, config_line, &config_len, NULL);
+        if (config_len > 0) {
+            config_line[config_len] = 0;
+
+            value root;
+            string error = picojson::parse(root, config_line);
+            if (!error.empty() || !root.is<object>()) {
+                throw ZookeeperException("Failed to parse zookeeper json: " + error);
+            }
+            const value::object& json_object = root.get<object>();
+            const value& host_json = json_object.at("host");
+            const value& port_json = json_object.at("port");
+            if (!host_json.is<string>() || !port_json.is<double>()) {
+                throw ZookeeperException("Invalid JSON received from zookeeper");
+            }
+            string host = host_json.get<string>();
+            int port = port_json.get<double>();
+            if (i != 0) {
+                oss << ",";
+            }
+            oss << host << ":" << port;
+        }
+    }
+    return oss.str();
+}
+
+void ZookeeperWatcher::handle_event_proxy(zhandle_t*, int type, int state, const char* path,
+                                          void* ctx) {
+    auto self = static_cast<ZookeeperWatcher*>(ctx);
+    self->handle_event(type, state, path);
+}
+
+void ZookeeperWatcher::handle_event(int type, int state, const char* path) {
+    if (type == ZOO_CHILD_EVENT && path == BROKERS_PATH) {
+        string brokers = get_brokers();
+        // TODO: Callback!
+    }   
+}
+
+} // cppkafka