void LogProcess::updated(const string& path)
{
if (znode + "/replicas" == path) {
regroup();
// Reset a watch on the replicas.
int ret = zk->getChildren(znode + "/replicas", true, NULL);
if (ret != ZOK) {
LOG(FATAL) << "Failed to set a watch on '" << znode << "/replicas"
<< "' in ZooKeeper: " << zk->message(ret);
}
} else {
CHECK(znode + "/coordinators" == path);
elect();
// Reset a watch on the coordinators.
int ret = zk->getChildren(znode + "/coordinators", true, NULL);
if (ret != ZOK) {
LOG(FATAL) << "Failed to set a watch on '" << znode << "/replicas"
<< "' in ZooKeeper: " << zk->message(ret);
}
}
}
void LogProcess::regroup()
{
vector<string> results;
int ret = zk->getChildren(znode + "/replicas", false, &results);
if (ret != ZOK) {
LOG(FATAL) << "Failed to get children of '" << znode << "/replicas"
<< "' in ZooKeeper: " << zk->message(ret);
}
set<UPID> current;
set<UPID> added;
set<UPID> removed;
foreach (const string& result, results) {
string s;
int ret = zk->get(znode + "/replicas/" + result, false, &s, NULL);
UPID pid = s;
current.insert(pid);
}
void LogProcess::connected()
{
LOG(INFO) << "Log connected to ZooKeeper";
int ret;
string result;
// Assume the znode that was created does not end with a "/".
CHECK(znode.size() == 0 || znode.at(znode.size() - 1) != '/');
// Create directory path znodes as necessary.
size_t index = znode.find("/", 0);
while (index < string::npos) {
// Get out the prefix to create.
index = znode.find("/", index + 1);
string prefix = znode.substr(0, index);
LOG(INFO) << "Log trying to create znode '"
<< prefix << "' in ZooKeeper";
// Create the node (even if it already exists).
ret = zk->create(
prefix,
"",
ZOO_OPEN_ACL_UNSAFE,
// ZOO_CREATOR_ALL_ACL, // needs authentication
0,
&result);
if (ret != ZOK && ret != ZNODEEXISTS) {
LOG(FATAL) << "Failed to create '" << prefix
<< "' in ZooKeeper: " << zk->message(ret);
}
}
// Now create the "replicas" znode.
LOG(INFO) << "Log trying to create znode '" << znode
<< "/replicas" << "' in ZooKeeper";
// Create the node (even if it already exists).
ret = zk->create(znode + "/replicas", "", ZOO_OPEN_ACL_UNSAFE,
// ZOO_CREATOR_ALL_ACL, // needs authentication
0, &result);
if (ret != ZOK && ret != ZNODEEXISTS) {
LOG(FATAL) << "Failed to create '" << znode << "/replicas"
<< "' in ZooKeeper: " << zk->message(ret);
}
// Now create the "coordinators" znode.
LOG(INFO) << "Log trying to create znode '" << znode
<< "/coordinators" << "' in ZooKeeper";
// Create the node (even if it already exists).
ret = zk->create(znode + "/coordinators", "", ZOO_OPEN_ACL_UNSAFE,
// ZOO_CREATOR_ALL_ACL, // needs authentication
0, &result);
if (ret != ZOK && ret != ZNODEEXISTS) {
LOG(FATAL) << "Failed to create '" << znode << "/coordinators"
<< "' in ZooKeeper: " << zk->message(ret);
}
// Okay, create our replica, group, and coordinator.
replica = new ReplicaProcess(file);
spawn(replica);
group = new GroupProcess();
spawn(group);
coordinator = new Coordinator(quorum, replica, group);
// Set a watch on the replicas.
ret = zk->getChildren(znode + "/replicas", true, NULL);
if (ret != ZOK) {
LOG(FATAL) << "Failed to set a watch on '" << znode << "/replicas"
<< "' in ZooKeeper: " << zk->message(ret);
}
// Set a watch on the coordinators.
ret = zk->getChildren(znode + "/coordinators", true, NULL);
if (ret != ZOK) {
LOG(FATAL) << "Failed to set a watch on '" << znode << "/replicas"
<< "' in ZooKeeper: " << zk->message(ret);
}
// Add an ephemeral znode for our replica and coordinator.
ret = zk->create(znode + "/replicas/", replica->self(), ZOO_OPEN_ACL_UNSAFE,
// ZOO_CREATOR_ALL_ACL, // needs authentication
ZOO_SEQUENCE | ZOO_EPHEMERAL, &result);
if (ret != ZOK) {
LOG(FATAL) << "Failed to create an ephmeral node at '" << znode
<< "/replica/" << "' in ZooKeeper: " << zk->message(ret);
}
ret = zk->create(znode + "/coordinators/", "", ZOO_OPEN_ACL_UNSAFE,
// ZOO_CREATOR_ALL_ACL, // needs authentication
ZOO_SEQUENCE | ZOO_EPHEMERAL, &result);
if (ret != ZOK) {
LOG(FATAL) << "Failed to create an ephmeral node at '" << znode
<< "/replica/" << "' in ZooKeeper: " << zk->message(ret);
}
// Save the sequence id but only grab the basename, e.g.,
// "/path/to/znode/000000131" => "000000131".
result = utils::os::basename(result);
try {
id = boost::lexical_cast<uint64_t>(result);
} catch (boost::bad_lexical_cast&) {
LOG(FATAL) << "Failed to convert '" << result << "' into an integer";
}
// Run an election!
elect();
}