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Better handling extended protocol messages in the event of busy pool (#155)

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* Better handling for checkout errors during extended protocol messages

* Fix specs

* comment
This commit is contained in:
Mostafa Abdelraouf
2022-09-01 17:02:39 -05:00
committed by GitHub
parent 36339bd96f
commit 7f20dc3054
1 changed files with 29 additions and 21 deletions
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50
src/client.rs
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@@ -600,12 +600,6 @@ where
message_result = read_message(&mut self.read) => message_result?
};
// Avoid taking a server if the client just wants to disconnect.
if message[0] as char == 'X' {
debug!("Client disconnecting");
return Ok(());
}
// Handle admin database queries.
if self.admin {
debug!("Handling admin command");
@@ -613,6 +607,25 @@ where
continue;
}
match message[0] as char {
// Buffer extended protocol messages even if we do not have
// a server connection yet. Hopefully, when we get the S message
// we'll be able to allocate a connection. Also, clients do not expect
// the server to respond to these messages so even if we were not able to
// allocate a connection, we wouldn't be able to send back an error message
// to the client so we buffer them and defer the decision to error out or not
// to when we get the S message
'P' | 'B' | 'D' | 'E' => {
self.buffer.put(&message[..]);
continue;
}
'X' => {
debug!("Client disconnecting");
return Ok(());
}
_ => (),
}
// Get a pool instance referenced by the most up-to-date
// pointer. This ensures we always read the latest config
// when starting a query.
@@ -714,22 +727,17 @@ where
conn
}
Err(err) => {
// Clients do not expect to get SystemError followed by ReadyForQuery in the middle
// of extended protocol submission. So we will hold off on sending the actual error
// message to the client until we get 'S' message
match message[0] as char {
'P' | 'B' | 'E' | 'D' => (),
_ => {
error_response(
&mut self.write,
"could not get connection from the pool",
)
.await?;
}
};
// Client is attempting to get results from the server,
// but we were unable to grab a connection from the pool
// We'll send back an error message and clean the extended
// protocol buffer
if message[0] as char == 'S' {
error!("Got Sync message but failed to get a connection from the pool");
self.buffer.clear();
}
error_response(&mut self.write, "could not get connection from the pool")
.await?;
error!("Could not get connection from pool: {:?}", err);
continue;
}
};