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package org.apache.http.conn;

import java.io.IOException;
import java.util.concurrent.TimeUnit;

import org.apache.http.HttpClientConnection;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.protocol.HttpContext;

Represents a manager of persistent client connections.

The purpose of an HTTP connection manager is to serve as a factory for new
HTTP connections, manage persistent connections and synchronize access to
persistent connections making sure that only one thread of execution can
have access to a connection at a time.


Implementations of this interface must be thread-safe. Access to shared
data must be synchronized as methods of this interface may be executed
from multiple threads.

Since:
4.3/**
 * Represents a manager of persistent client connections.
 * <p>
 * The purpose of an HTTP connection manager is to serve as a factory for new
 * HTTP connections, manage persistent connections and synchronize access to
 * persistent connections making sure that only one thread of execution can
 * have access to a connection at a time.
 * </p>
 * <p>
 * Implementations of this interface must be thread-safe. Access to shared
 * data must be synchronized as methods of this interface may be executed
 * from multiple threads.
 * </p>
 *
 * @since 4.3
 */
public interface HttpClientConnectionManager {

    
Returns a new ConnectionRequest, from which a HttpClientConnection can be obtained or the request can be aborted. 
 Please note that newly allocated connections can be returned in the closed state. The consumer of that connection is responsible for fully establishing the route the to the connection target by calling connect in order to connect directly to the target or to the first proxy hop, optionally calling upgrade method to upgrade the connection after having executed CONNECT method to all intermediate proxy hops and and finally calling routeComplete to mark the route as fully completed. 
Params:
route – HTTP route of the requested connection.
state – expected state of the connection or null if the connection is not expected to carry any state./**
     * Returns a new {@link ConnectionRequest}, from which a
     * {@link HttpClientConnection} can be obtained or the request can be
     * aborted.
     * <p>
     * Please note that newly allocated connections can be returned
     * in the closed state. The consumer of that connection is responsible
     * for fully establishing the route the to the connection target
     * by calling {@link #connect(org.apache.http.HttpClientConnection,
     *   org.apache.http.conn.routing.HttpRoute, int,
     *   org.apache.http.protocol.HttpContext) connect} in order to connect
     * directly to the target or to the first proxy hop, optionally calling
     * {@link #upgrade(org.apache.http.HttpClientConnection,
     *   org.apache.http.conn.routing.HttpRoute,
     *   org.apache.http.protocol.HttpContext) upgrade} method to upgrade
     * the connection after having executed {@code CONNECT} method to
     * all intermediate proxy hops and and finally calling {@link #routeComplete(
     *  org.apache.http.HttpClientConnection,
     *  org.apache.http.conn.routing.HttpRoute,
     *  org.apache.http.protocol.HttpContext) routeComplete} to mark the route
     *  as fully completed.
     * </p>
     *
     * @param route HTTP route of the requested connection.
     * @param state expected state of the connection or {@code null}
     *              if the connection is not expected to carry any state.
     */
    ConnectionRequest requestConnection(HttpRoute route, Object state);

    
Releases the connection back to the manager making it potentially re-usable by other consumers. Optionally, the maximum period of how long the manager should keep the connection alive can be defined using validDuration and timeUnit parameters. 
Params:
conn –      the managed connection to release.
validDuration – the duration of time this connection is valid for reuse.
timeUnit – the time unit.
See Also:
closeExpiredConnections()/**
     * Releases the connection back to the manager making it potentially
     * re-usable by other consumers. Optionally, the maximum period
     * of how long the manager should keep the connection alive can be
     * defined using {@code validDuration} and {@code timeUnit}
     * parameters.
     *
     * @param conn      the managed connection to release.
     * @param validDuration the duration of time this connection is valid for reuse.
     * @param timeUnit the time unit.
     *
     * @see #closeExpiredConnections()
     */
    void releaseConnection(
            HttpClientConnection conn, Object newState, long validDuration, TimeUnit timeUnit);

    
Connects the underlying connection socket to the connection target in case
of a direct route or to the first proxy hop in case of a route via a proxy
(or multiple proxies).
Params:
conn – the managed connection.
route – the route of the connection.
connectTimeout – connect timeout in milliseconds.
context – the actual HTTP context.
Throws:
IOException – /**
     * Connects the underlying connection socket to the connection target in case
     * of a direct route or to the first proxy hop in case of a route via a proxy
     * (or multiple proxies).
     *
     * @param conn the managed connection.
     * @param route the route of the connection.
     * @param connectTimeout connect timeout in milliseconds.
     * @param context the actual HTTP context.
     * @throws IOException
     */
    void connect(
            HttpClientConnection conn,
            HttpRoute route,
            int connectTimeout,
            HttpContext context) throws IOException;

    
Upgrades the underlying connection socket to TLS/SSL (or another layering protocol) after having executed CONNECT method to all intermediate proxy hops 
Params:
conn – the managed connection.
route – the route of the connection.
context – the actual HTTP context.
Throws:
IOException – /**
     * Upgrades the underlying connection socket to TLS/SSL (or another layering
     * protocol) after having executed {@code CONNECT} method to all
     * intermediate proxy hops
     *
     * @param conn the managed connection.
     * @param route the route of the connection.
     * @param context the actual HTTP context.
     * @throws IOException
     */
    void upgrade(
            HttpClientConnection conn,
            HttpRoute route,
            HttpContext context) throws IOException;

    
Marks the connection as fully established with all its intermediate
hops completed.
Params:
conn – the managed connection.
route – the route of the connection.
context – the actual HTTP context.
Throws:
IOException – /**
     * Marks the connection as fully established with all its intermediate
     * hops completed.
     *
     * @param conn the managed connection.
     * @param route the route of the connection.
     * @param context the actual HTTP context.
     * @throws IOException
     */
    void routeComplete(
            HttpClientConnection conn,
            HttpRoute route,
            HttpContext context) throws IOException;

    
Closes idle connections in the pool.

Open connections in the pool that have not been used for the
timespan given by the argument will be closed.
Currently allocated connections are not subject to this method.
Times will be checked with milliseconds precision


All expired connections will also be closed.

Params:
idletime –  the idle time of connections to be closed
timeUnit –  the unit for the idletime
See Also:
closeExpiredConnections()/**
     * Closes idle connections in the pool.
     * <p>
     * Open connections in the pool that have not been used for the
     * timespan given by the argument will be closed.
     * Currently allocated connections are not subject to this method.
     * Times will be checked with milliseconds precision
     * </p>
     * <p>
     * All expired connections will also be closed.
     * </p>
     *
     * @param idletime  the idle time of connections to be closed
     * @param timeUnit     the unit for the {@code idletime}
     *
     * @see #closeExpiredConnections()
     */
    void closeIdleConnections(long idletime, TimeUnit timeUnit);

    
Closes all expired connections in the pool.

Open connections in the pool that have not been used for
the timespan defined when the connection was released will be closed.
Currently allocated connections are not subject to this method.
Times will be checked with milliseconds precision.

/**
     * Closes all expired connections in the pool.
     * <p>
     * Open connections in the pool that have not been used for
     * the timespan defined when the connection was released will be closed.
     * Currently allocated connections are not subject to this method.
     * Times will be checked with milliseconds precision.
     * </p>
     */
    void closeExpiredConnections();

    
Shuts down this connection manager and releases allocated resources.
This includes closing all connections, whether they are currently
used or not.
/**
     * Shuts down this connection manager and releases allocated resources.
     * This includes closing all connections, whether they are currently
     * used or not.
     */
    void shutdown();

}