Add queue-related functions to the database interface.

These functions, in general following the same HTTP-verb
approach as the rest of the database interface, are for
use with both the HTTP API and the queue processor.

lib/www/server/lib/db/index.js

@@ -10,5 +10,6 @@ module.exports = {
 	configuration: require('./configuration'),
 	info: require('./info'),
 	meta: require('./meta'),
-	navdata: require('./navdata')
+	navdata: require('./navdata'),
+	queue: require('./queue')
 };

lib/www/server/lib/db/queue/delete.js

@@ -0,0 +1,24 @@
+
+const { transaction, pool } = require('../connection');
+
+async function post(queueId/*unused*/, item_id) {
+
+	const client = await pool.connect();
+
+	const text = `
+		UPDATE queue_items
+		SET status = 'cancelled'
+		WHERE status = 'queued'
+			AND (item_id = $1
+				OR parent_id = $1);
+	`;
+
+	const res = await client.query(text, [item_id]);
+	client.release();
+	if (!res.rowCount) {
+		throw { status: 404, message: "No cancellable requests" };
+	}
+
+}
+
+module.exports = post;

lib/www/server/lib/db/queue/get.js

@@ -0,0 +1,72 @@
+const { pool } = require('../connection');
+
+async function get (queueId/*unused*/, opts = {}) {
+	const client = await pool.connect();
+
+	const validStatuses = [
+		'queued',
+		'cancelled',
+		'failed',
+		'sent'
+	];
+
+	const validOrders = {
+		created_on: "created_on",
+		updated_on: "updated_on",
+		not_before: "not_before",
+		item_id: "item_id",
+		status: "status",
+		parent_id: "parent_id",
+		project: "payload->'project'",
+		sequence: "payload->'sequence'"
+	};
+
+	const limit = Math.min(Math.abs(opts.limit) || 100, 1000);
+	const offset = Math.abs(opts.offset) || 0;
+	const order = validOrders[opts.order] || "updated_on";
+	const dir = (!opts.dir || opts.dir == "-")
+		? "DESC"
+		: "ASC";
+
+	const validStatus = validStatuses.includes(opts.status);
+	const status = validStatus ? opts.status : 1;
+
+	const hasProject = "project" in opts;
+	const hasSequence = "sequence" in opts;
+	const project = hasProject
+		? opts.project
+		: 1;
+	const sequence = hasSequence
+		? opts.sequence
+		: 1;
+
+	const restrict1 = validStatus
+		? "status = $3"
+		: "$3 = $3";
+
+	const restrict2 = hasProject
+		? "AND payload->>'project' = $4"
+		: "AND $4 = $4";
+
+	// Yes, technically a user could restrict by sequence
+	// only, without specifying a project. Let's call that
+	// a feature.
+	const restrict3 = hasSequence
+		? "AND payload->>'sequence' = $5"
+		: "AND $5 = $5";
+
+	const text = `
+		SELECT *
+		FROM queue_items
+		WHERE ${restrict1} ${restrict2} ${restrict3}
+		ORDER BY ${order} ${dir}
+		LIMIT $1
+		OFFSET $2;
+	`;
+
+	const res = await client.query(text, [limit, offset, status, project, sequence]);
+	client.release();
+	return res.rows;
+}
+
+module.exports = get;

lib/www/server/lib/db/queue/index.js

@@ -0,0 +1,6 @@
+module.exports = {
+	get: require('./get'),
+	post: require('./post'),
+	put: require('./put'),
+	delete: require('./delete')
+};

lib/www/server/lib/db/queue/post.js

@@ -0,0 +1,38 @@
+
+const { transaction, pool } = require('../connection');
+
+async function post(queueId/*unused*/, payload, parent_id) {
+
+	// Technically the API only supports an array payload,
+	// but we'll be permissive and accept a single request
+	// object.
+	if (!Array.isArray(payload)) {
+		payload = [payload];
+	}
+
+	const client = await pool.connect();
+
+	await transaction.begin(client);
+	for (const {project, sequence} of payload) {
+
+		if ([project, sequence].some(v => typeof v === "undefined")) {
+			throw { status: 400, message: "Malformed request" };
+		}
+
+		// If we got here, the request is probably OK.
+		// Most fields just take default values.
+		const text = `
+			INSERT INTO queue_items (payload, parent_id)
+			VALUES ($1, $2);
+		`;
+
+		await client.query(text, [{project, sequence}, parent_id]);
+
+	}
+	await transaction.commit(client);
+	client.release();
+
+
+}
+
+module.exports = post;

lib/www/server/lib/db/queue/put.js

@@ -0,0 +1,49 @@
+const { pool } = require('../connection');
+
+/**
+ * Stringify arrays.
+ *
+ * node-postgres has an issue in that it transforms
+ * JSON array objects into PostgreSQL arrays instead
+ * of JSON arrays, which causes a problem for json/jsonb
+ * fields.
+ *
+ * Note: this is a feature not a bug. See:
+ * https://github.com/brianc/node-postgres/issues/442
+ */
+function formatValue(value) {
+	if (Array.isArray(value)) {
+		return JSON.stringify(value);
+	} else {
+		return value;
+	}
+}
+
+async function put (item_id, values) {
+	const client = await pool.connect();
+
+	const updateable = [ "status", "results", "parent_id" ];
+	const fields = [];
+	const params = [item_id];
+
+	for (const field of updateable) {
+		if (field in values) {
+			fields.push(`${field} = $${params.length+1}`);
+			params.push(formatValue(values[field]));
+		}
+	}
+
+	const text = `
+		UPDATE queue_items
+		SET
+			${fields.join(",\n")}
+		WHERE item_id = $1
+		RETURNING *;
+	`;
+
+	const res = await client.query(text, params);
+	client.release();
+	return res.rows[0];
+}
+
+module.exports = put;