Language servers

When DataMind Oda answers a question about code, for example where a name is defined or where it is used, it asks a language server: a helper program on your computer that understands one programming language. This page explains how Oda chooses and sets up these servers, what their limits are, and what their messages mean. The questions Oda asks and the answers it shows are covered in Code navigation.

How Oda chooses a server

Oda picks the server by the file's type: the part of the file name after the last dot. One file type is handled by one server at most.

• One for each type. Two servers cannot claim the same file type, so every question about a file of that type goes through the same server.
• No match, no answer. If no server covers the file's type, Oda reports that code navigation is unavailable for the file instead of guessing. A name with no dot, or one that starts with a dot, has no type.
• Files from the chat's folder. Oda reads the file from the chat's workspace folder as it is at that moment, so an answer never comes from an old copy.

Servers Oda installs for you

Some language servers are installed when they are first needed. The first question that needs one starts its installation, and installing needs an internet connection on the computer. Until the installation finishes, the question is answered with:

<language> code navigation is being set up: its language server is still installing. Try again in a minute.

The message begins with the language whose server is being installed. Ask again in a minute: the installation continues on its own, and questions that need the same server share that one installation.

Once installed, the server stays in Oda's own storage on the computer. Later questions and later starts of Oda reuse it, and changing which servers are set up does not remove it.

If the installation fails, the question is answered with:

<language> code navigation is unavailable: its language server could not be installed (<reason>). The next lsp call tries again.

The reason in brackets comes from the installation itself. The next question tries again; if it keeps failing, check the computer's internet connection, and if it still fails, contact your DataMind OS administrator with the message.

Servers that run from programs on your computer

Some Oda setups do not install a language server: a program that is already on the computer serves the answers, and Oda starts that program and talks to it.

Before starting it, Oda filters the environment it passes to that program:

• Entries whose names look like credentials, for example names containing KEY, PASSWORD, SECRET or TOKEN, are not passed on.
• Oda's own internal entries are not passed on either.
• Values set for that server are added after the filter.

Apart from how they are set up, both kinds of server behave the same: Oda asks, the server answers.

When a question fails

A server that cannot answer does not guess; Oda reports the failure in the chat:

• Not supported. If the server does not offer the kind of answer Oda asked for, the failure says the server does not support it.
• Unsupported format. If the server reports positions in a format Oda does not support, the question fails and the failure says which format the server wanted.
• Server stopped. If the server stops while answering, Oda says it exited, includes the last part of what the server wrote, and retries the question once with a fresh server.
• Stopped question. A question that is cancelled or stopped, or that reaches its time limit, is reported as aborted.

A server that failed is not reused.

Limits

• One server per file type. Two servers cannot cover the same type, so each type has one answerer.
• One question at a time per server and folder. A later question that needs the same server in the same folder waits its turn; questions for different folders can run side by side.
• No sandbox. Language servers run as ordinary programs on your computer, outside the command sandbox; the file limits of the chat's access mode apply to commands, not to them. See Command sandboxing and approvals.
• Text files, up to 4 MB. Oda reads a file for a question only when it can read it as text and it is no larger than 4 MB; a file over that size, or one it cannot read as text, is refused before a server starts.
• Force-closed Oda. If Oda is force-closed, a language server it started can stay on the computer until it exits by itself.

Questions, answered

What is a language server?

A helper program on your computer that understands one programming language. When Oda answers a question about a code file, it asks the language server for that file's type, and the server works out the answer, for example where a name is defined or where it is used. See Code navigation.

How does Oda decide which language server to use?

By the file's type: the part of the file name after the last dot. Each type has one server at most, so every file of that type goes to the same server. If no server covers the type, Oda reports that code navigation is unavailable for the file.

Does Oda install software on my computer for code navigation?

For some file types, yes. The first question that needs a server downloads and installs it in Oda's own storage on the computer, and later questions and later starts of Oda reuse it. The first installation needs an internet connection.

What does "code navigation is being set up" mean?

The server for that file's type is still installing, and the question was answered before the installation finished. Ask again in a minute; the installation continues on its own.

Why did the language server fail to install?

The installation did not finish, and the message names the reason it reported. The next question tries to install it again. A first-time installation needs an internet connection on the computer; if it keeps failing, contact your DataMind OS administrator with the message.

Can Oda use a language server that is already on my computer?

Some Oda setups use a program that is already on the computer as the language server instead of installing one. That is arranged where Oda is set up, not from a chat; ask your DataMind OS administrator.

Do the chat's access limits apply to language servers?

No. Language servers run as ordinary programs, outside the command sandbox; the file limits of the chat's access mode apply to commands, not to them. See Command sandboxing and approvals.

Why does a code question sometimes wait?

Questions that need the same language server in the same folder are answered one at a time, so a later question waits its turn. Questions for different folders can run side by side.

What happens to a language server if I force-quit Oda?

Normally a language server closes when Oda closes. If Oda is force-closed, a server it started can stay on the computer until it exits by itself.

Does Oda leave my files open in the server?

No. Oda reads the file when the question runs and closes it again when the question is done; nothing stays open between questions.