misc: Add method comments and update docs for distributed procedures

[hantangwangd]

Description

This PR updates the procedure development documentation to align with the interface and implementation logic adjustments in the distributed procedure code, and adds comments to some abstract methods in class DistributedProcedure.

Motivation and Context

Ensures the procedure development documentation more accurate.

Impact

N/A

Test Plan

N/A

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Release Notes

== NO RELEASE NOTE ==

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Updates distributed procedure documentation to match the current interface and adds clarifying JavaDoc for key lifecycle methods in DistributedProcedure, including context creation and execution phases.

Sequence diagram for distributed procedure execution lifecycle

sequenceDiagram
    actor Client
    participant PrestoCoordinator
    participant ConnectorMetadata
    participant DistributedProcedure
    participant WorkerTasks

    Client->>PrestoCoordinator: invoke distributed procedure
    PrestoCoordinator->>ConnectorMetadata: get DistributedProcedure
    ConnectorMetadata-->>PrestoCoordinator: DistributedProcedure instance

    PrestoCoordinator->>DistributedProcedure: createContext(arguments)
    DistributedProcedure-->>PrestoCoordinator: ConnectorProcedureContext
    PrestoCoordinator->>ConnectorMetadata: bind ConnectorProcedureContext

    PrestoCoordinator->>DistributedProcedure: begin(session, procedureContext, tableLayoutHandle, arguments)
    DistributedProcedure-->>PrestoCoordinator: ConnectorDistributedProcedureHandle

    PrestoCoordinator->>WorkerTasks: execute distributed work using procedureHandle
    WorkerTasks-->>PrestoCoordinator: Collection<Slice> fragments

    PrestoCoordinator->>DistributedProcedure: finish(session, procedureContext, procedureHandle, fragments)
    DistributedProcedure-->>PrestoCoordinator: commit complete

    PrestoCoordinator-->>Client: procedure completed

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Class diagram for DistributedProcedure lifecycle methods

classDiagram
    class DistributedProcedure {
        <<abstract>>
        -DistributedProcedureType type
        +DistributedProcedureType getType()
        +ConnectorDistributedProcedureHandle begin(ConnectorSession session, ConnectorProcedureContext procedureContext, ConnectorTableLayoutHandle tableLayoutHandle, Object[] arguments)
        +void finish(ConnectorSession session, ConnectorProcedureContext procedureContext, ConnectorDistributedProcedureHandle procedureHandle, Collection~Slice~ fragments)
        +ConnectorProcedureContext createContext(Object[] arguments)
    }

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File-Level Changes

Change	Details	Files
Add lifecycle and context-creation JavaDoc to DistributedProcedure to clarify how distributed procedures are executed and how context is managed.	Document the responsibilities of begin() as preparatory work for starting distributed procedure execution. Document the responsibilities of finish() as the centralized final commit after distributed execution completes. Document createContext() as the hook for creating connector- or subtype-specific procedure context, its invocation timing, binding to ConnectorMetadata, and its use in begin() and finish().	presto-spi/src/main/java/com/facebook/presto/spi/procedure/DistributedProcedure.java
Align procedure development documentation with the current distributed procedure interface and lifecycle semantics.	Update developer docs for procedures to describe the distributed procedure lifecycle consistent with the begin/finish/createContext semantics. Clarify how distributed procedure context is created, bound, and used during execution in the documentation.	presto-docs/src/main/sphinx/develop/procedures.rst

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[sourcery-ai]

Hey - I've found 2 issues, and left some high level feedback:

• The new Javadoc comments for begin and finish should be updated to end with periods and use consistent verb tense/style (e.g., "Performs preparatory work..." vs "Perform the preparatory work...") to match the rest of the codebase’s Javadoc conventions.
• Consider referencing the method names in comments with {@code begin()}/{@code finish()} (or {@link #begin(...)}/{@link #finish(...)}) in the createContext Javadoc so that tooling can correctly link them and the text is clearer.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The new Javadoc comments for `begin` and `finish` should be updated to end with periods and use consistent verb tense/style (e.g., "Performs preparatory work..." vs "Perform the preparatory work...") to match the rest of the codebase’s Javadoc conventions.
- Consider referencing the method names in comments with `{@code begin()}`/`{@code finish()}` (or `{@link #begin(...)}`/`{@link #finish(...)}`) in the `createContext` Javadoc so that tooling can correctly link them and the text is clearer.

## Individual Comments

### Comment 1
<location> `presto-spi/src/main/java/com/facebook/presto/spi/procedure/DistributedProcedure.java:47-55` </location>
<code_context>
-   public ConnectorProcedureContext createContext()
+   public ConnectorProcedureContext createContext(Object... arguments);

    /**
     * Performs the preparatory work required when starting the execution of this distributed procedure
</code_context>

<issue_to_address>
**suggestion:** Clarify what the returned handle from `begin` represents and its lifecycle.

The Javadoc for `begin` describes the preparatory work but not what the returned `ConnectorDistributedProcedureHandle` is contractually supposed to represent or how it should be used (e.g., whether it must be passed unchanged to `finish`, whether it needs to be stable/serializable). Please add a brief note on its semantics and lifecycle to make the API contract clearer for connector authors.

```suggestion
    /**
     * Performs the preparatory work required when starting the execution of this distributed procedure.
     * <p>
     * The returned {@link ConnectorDistributedProcedureHandle} represents the logical execution of a single
     * invocation of this distributed procedure. It:
     * <ul>
     *     <li>MUST be passed, unchanged, to {@link #finish(ConnectorSession, ConnectorProcedureContext, ConnectorDistributedProcedureHandle, Collection)}.</li>
     *     <li>MUST be stable for the lifetime of that invocation (i.e., identifies one specific run of the procedure).</li>
     *     <li>SHOULD be serializable and safe to use across tasks or nodes if the implementation needs to reference it in distributed execution.</li>
     * </ul>
     * Implementations may encode connector-specific state in the handle, but must treat it as an opaque token
     * from the perspective of callers.
     */
    public abstract ConnectorDistributedProcedureHandle begin(ConnectorSession session, ConnectorProcedureContext procedureContext, ConnectorTableLayoutHandle tableLayoutHandle, Object[] arguments);

    /**
     * Performs the work required for the final centralized commit, after all distributed execution tasks have
     * completed for a single invocation of this distributed procedure.
     * <p>
     * The {@code procedureHandle} passed here is the same handle returned from {@link #begin(ConnectorSession,
     * ConnectorProcedureContext, ConnectorTableLayoutHandle, Object[])} and identifies the procedure invocation
     * whose fragments are being finalized.
     */
    public abstract void finish(ConnectorSession session, ConnectorProcedureContext procedureContext, ConnectorDistributedProcedureHandle procedureHandle, Collection<Slice> fragments);
```
</issue_to_address>

### Comment 2
<location> `presto-docs/src/main/sphinx/develop/procedures.rst:428` </location>
<code_context>
-                   IcebergProcedureContext::new);
+                   ((session, procedureContext, tableHandle, fragments) -> finishCallDistributedProcedure(session, (IcebergProcedureContext) procedureContext, tableHandle, fragments)),
+                   arguments -> {
+                       checkArgument(arguments.length == 2, "invalid arguments count: " + arguments.length);
+                       checkArgument(arguments[0] instanceof Table && arguments[1] instanceof Transaction, "Invalid arguments, required: [Table, Transaction]");
+                       return new IcebergProcedureContext((Table) arguments[0], (Transaction) arguments[1]);
</code_context>

<issue_to_address>
**suggestion (typo):** Consider correcting the error message to use "argument count" instead of "arguments count".

"invalid arguments count" is ungrammatical. Please change it to "invalid argument count" or "invalid number of arguments" for clearer messaging.

```suggestion
                       checkArgument(arguments.length == 2, "invalid argument count: " + arguments.length);
```
</issue_to_address>

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[PingLiuPing]

Thank you.

[steveburnett]

LGTM! (docs)

Pull branch, local doc build, looks great. Thank you!