peermux.c

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/*
 * Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <ipxe/uri.h>
#include <ipxe/xferbuf.h>
#include <ipxe/job.h>
#include <ipxe/peerblk.h>
#include <ipxe/peermux.h>

/** @file
 *
 * Peer Content Caching and Retrieval (PeerDist) protocol multiplexer
 *
 */

/**
 * Free PeerDist download multiplexer
 *
 * @v refcnt            Reference count
 */
static void peermux_free ( struct refcnt *refcnt ) {
        struct peerdist_multiplexer *peermux =
                container_of ( refcnt, struct peerdist_multiplexer, refcnt );

        uri_put ( peermux->uri );
        xferbuf_free ( &peermux->buffer );
        free ( peermux );
}

/**
 * Close PeerDist download multiplexer
 *
 * @v peermux           PeerDist download multiplexer
 * @v rc                Reason for close
 */
static void peermux_close ( struct peerdist_multiplexer *peermux, int rc ) {
        unsigned int i;

        /* Stop block download initiation process */
        process_del ( &peermux->process );

        /* Shut down all block downloads */
        for ( i = 0 ; i < PEERMUX_MAX_BLOCKS ; i++ )
                intf_shutdown ( &peermux->block[i].xfer, rc );

        /* Shut down all other interfaces (which may be connected to
         * the same object).
         */
        intf_nullify ( &peermux->info ); /* avoid potential loops */
        intf_shutdown ( &peermux->xfer, rc );
        intf_shutdown ( &peermux->info, rc );
}

/**
 * Report progress of PeerDist download
 *
 * @v peermux           PeerDist download multiplexer
 * @v progress          Progress report to fill in
 * @ret ongoing_rc      Ongoing job status code (if known)
 */
static int peermux_progress ( struct peerdist_multiplexer *peermux,
                              struct job_progress *progress ) {
        struct peerdist_statistics *stats = &peermux->stats;
        unsigned int percentage;

        /* Construct PeerDist status message */
        if ( stats->total ) {
                percentage = ( ( 100 * stats->local ) / stats->total );
                snprintf ( progress->message, sizeof ( progress->message ),
                           "%3d%% from %d peers", percentage, stats->peers );
        }

        return 0;
}

/**
 * Receive content information
 *
 * @v peermux           PeerDist download multiplexer
 * @v iobuf             I/O buffer
 * @v meta              Data transfer metadata
 * @ret rc              Return status code
 */
static int peermux_info_deliver ( struct peerdist_multiplexer *peermux,
                                  struct io_buffer *iobuf,
                                  struct xfer_metadata *meta ) {
        int rc;

        /* Add data to buffer */
        if ( ( rc = xferbuf_deliver ( &peermux->buffer, iobuf, meta ) ) != 0 )
                goto err;

        return 0;

 err:
        peermux_close ( peermux, rc );
        return rc;
}

/**
 * Close content information interface
 *
 * @v peermux           PeerDist download multiplexer
 * @v rc                Reason for close
 */
static void peermux_info_close ( struct peerdist_multiplexer *peermux, int rc ){
        struct xfer_buffer *buffer = &peermux->buffer;
        struct peerdist_info *info = &peermux->cache.info;
        size_t len;

        /* Terminate download on error */
        if ( rc != 0 )
                goto err;

        /* Successfully closing the content information interface
         * indicates that the content information has been fully
         * received, and initiates the actual PeerDist download.
         */

        /* Shut down content information interface */
        intf_shutdown ( &peermux->info, rc );

        /* Parse content information */
        if ( ( rc = peerdist_info ( buffer->data, buffer->len, info ) ) != 0 ) {
                DBGC ( peermux, "PEERMUX %p could not parse content info: %s\n",
                       peermux, strerror ( rc ) );
                goto err;
        }

        /* Notify recipient of total download size */
        len = ( info->trim.end - info->trim.start );
        if ( ( rc = xfer_seek ( &peermux->xfer, len ) ) != 0 ) {
                DBGC ( peermux, "PEERMUX %p could not presize buffer: %s\n",
                       peermux, strerror ( rc ) );
                goto err;
        }
        xfer_seek ( &peermux->xfer, 0 );

        /* Start block download process */
        process_add ( &peermux->process );

        return;

 err:
        peermux_close ( peermux, rc );
}

/**
 * Initiate multiplexed block download
 *
 * @v peermux           PeerDist download multiplexer
 */
static void peermux_step ( struct peerdist_multiplexer *peermux ) {
        struct peerdist_info *info = &peermux->cache.info;
        struct peerdist_info_segment *segment = &peermux->cache.segment;
        struct peerdist_info_block *block = &peermux->cache.block;
        struct peerdist_multiplexed_block *peermblk;
        unsigned int next_segment;
        unsigned int next_block;
        int rc;

        /* Stop initiation process if all block downloads are busy */
        peermblk = list_first_entry ( &peermux->idle,
                                      struct peerdist_multiplexed_block, list );
        if ( ! peermblk ) {
                process_del ( &peermux->process );
                return;
        }

        /* Increment block index */
        next_block = ( block->index + 1 );

        /* Move to first/next segment, if applicable */
        if ( next_block >= segment->blocks ) {

                /* Reset block index */
                next_block = 0;

                /* Calculate segment index */
                next_segment = ( segment->info ? ( segment->index + 1 ) : 0 );

                /* If we have finished all segments and have no
                 * remaining block downloads, then we are finished.
                 */
                if ( next_segment >= info->segments ) {
                        process_del ( &peermux->process );
                        if ( list_empty ( &peermux->busy ) )
                                peermux_close ( peermux, 0 );
                        return;
                }

                /* Get content information segment */
                if ( ( rc = peerdist_info_segment ( info, segment,
                                                    next_segment ) ) != 0 ) {
                        DBGC ( peermux, "PEERMUX %p could not get segment %d "
                               "information: %s\n", peermux, next_segment,
                               strerror ( rc ) );
                        goto err;
                }
        }

        /* Get content information block */
        if ( ( rc = peerdist_info_block ( segment, block, next_block ) ) != 0 ){
                DBGC ( peermux, "PEERMUX %p could not get segment %d block "
                       "%d information: %s\n", peermux, segment->index,
                       next_block, strerror ( rc ) );
                goto err;
        }

        /* Ignore block if it lies entirely outside the trimmed range */
        if ( block->trim.start == block->trim.end ) {
                DBGC ( peermux, "PEERMUX %p skipping segment %d block %d\n",
                       peermux, segment->index, block->index );
                return;
        }

        /* Start downloading this block */
        if ( ( rc = peerblk_open ( &peermblk->xfer, peermux->uri,
                                   block ) ) != 0 ) {
                DBGC ( peermux, "PEERMUX %p could not start download for "
                       "segment %d block %d: %s\n", peermux, segment->index,
                       block->index, strerror ( rc ) );
                goto err;
        }

        /* Move to list of busy block downloads */
        list_del ( &peermblk->list );
        list_add_tail ( &peermblk->list, &peermux->busy );

        return;

 err:
        peermux_close ( peermux, rc );
}

/**
 * Receive data from multiplexed block download
 *
 * @v peermblk          PeerDist multiplexed block download
 * @v iobuf             I/O buffer
 * @v meta              Data transfer metadata
 * @ret rc              Return status code
 */
static int peermux_block_deliver ( struct peerdist_multiplexed_block *peermblk,
                                   struct io_buffer *iobuf,
                                   struct xfer_metadata *meta ) {
        struct peerdist_multiplexer *peermux = peermblk->peermux;

        /* Sanity check: all block downloads must use absolute
         * positions for all deliveries, since they run concurrently.
         */
        assert ( meta->flags & XFER_FL_ABS_OFFSET );

        /* We can't use a simple passthrough interface descriptor,
         * since there are multiple block download interfaces.
         */
        return xfer_deliver ( &peermux->xfer, iob_disown ( iobuf ), meta );
}

/**
 * Get multiplexed block download underlying data transfer buffer
 *
 * @v peermblk          PeerDist multiplexed download block
 * @ret xferbuf         Data transfer buffer, or NULL on error
 */
static struct xfer_buffer *
peermux_block_buffer ( struct peerdist_multiplexed_block *peermblk ) {
        struct peerdist_multiplexer *peermux = peermblk->peermux;

        /* We can't use a simple passthrough interface descriptor,
         * since there are multiple block download interfaces.
         */
        return xfer_buffer ( &peermux->xfer );
}

/**
 * Record peer discovery statistics
 *
 * @v peermblk          PeerDist multiplexed block download
 * @v peer              Selected peer (or NULL)
 * @v peers             List of available peers
 */
static void peermux_block_stat ( struct peerdist_multiplexed_block *peermblk,
                                 struct peerdisc_peer *peer,
                                 struct list_head *peers ) {
        struct peerdist_multiplexer *peermux = peermblk->peermux;
        struct peerdist_statistics *stats = &peermux->stats;
        struct peerdisc_peer *tmp;
        unsigned int count = 0;

        /* Record maximum number of available peers */
        list_for_each_entry ( tmp, peers, list )
                count++;
        if ( count > stats->peers )
                stats->peers = count;

        /* Update block counts */
        if ( peer )
                stats->local++;
        stats->total++;
        DBGC2 ( peermux, "PEERMUX %p downloaded %d/%d from %d peers\n",
                peermux, stats->local, stats->total, stats->peers );
}

/**
 * Close multiplexed block download
 *
 * @v peermblk          PeerDist multiplexed block download
 * @v rc                Reason for close
 */
static void peermux_block_close ( struct peerdist_multiplexed_block *peermblk,
                                  int rc ) {
        struct peerdist_multiplexer *peermux = peermblk->peermux;

        /* Move to list of idle downloads */
        list_del ( &peermblk->list );
        list_add_tail ( &peermblk->list, &peermux->idle );

        /* If any error occurred, terminate the whole multiplexer */
        if ( rc != 0 ) {
                peermux_close ( peermux, rc );
                return;
        }

        /* Restart data transfer interface */
        intf_restart ( &peermblk->xfer, rc );

        /* Restart block download initiation process */
        process_add ( &peermux->process );
}

/** Data transfer interface operations */
static struct interface_operation peermux_xfer_operations[] = {
        INTF_OP ( job_progress, struct peerdist_multiplexer *,
                  peermux_progress ),
        INTF_OP ( intf_close, struct peerdist_multiplexer *, peermux_close ),
};

/** Data transfer interface descriptor */
static struct interface_descriptor peermux_xfer_desc =
        INTF_DESC_PASSTHRU ( struct peerdist_multiplexer, xfer,
                             peermux_xfer_operations, info );

/** Content information interface operations */
static struct interface_operation peermux_info_operations[] = {
        INTF_OP ( xfer_deliver, struct peerdist_multiplexer *,
                  peermux_info_deliver ),
        INTF_OP ( intf_close, struct peerdist_multiplexer *,
                  peermux_info_close ),
};

/** Content information interface descriptor */
static struct interface_descriptor peermux_info_desc =
        INTF_DESC_PASSTHRU ( struct peerdist_multiplexer, info,
                             peermux_info_operations, xfer );

/** Block download data transfer interface operations */
static struct interface_operation peermux_block_operations[] = {
        INTF_OP ( xfer_deliver, struct peerdist_multiplexed_block *,
                  peermux_block_deliver ),
        INTF_OP ( xfer_buffer, struct peerdist_multiplexed_block *,
                  peermux_block_buffer ),
        INTF_OP ( peerdisc_stat, struct peerdist_multiplexed_block *,
                  peermux_block_stat ),
        INTF_OP ( intf_close, struct peerdist_multiplexed_block *,
                  peermux_block_close ),
};

/** Block download data transfer interface descriptor */
static struct interface_descriptor peermux_block_desc =
        INTF_DESC ( struct peerdist_multiplexed_block, xfer,
                    peermux_block_operations );

/** Block download initiation process descriptor */
static struct process_descriptor peermux_process_desc =
        PROC_DESC ( struct peerdist_multiplexer, process, peermux_step );

/**
 * Add PeerDist content-encoding filter
 *
 * @v xfer              Data transfer interface
 * @v info              Content information interface
 * @v uri               Original URI
 * @ret rc              Return status code
 */
int peermux_filter ( struct interface *xfer, struct interface *info,
                     struct uri *uri ) {
        struct peerdist_multiplexer *peermux;
        struct peerdist_multiplexed_block *peermblk;
        unsigned int i;

        /* Allocate and initialise structure */
        peermux = zalloc ( sizeof ( *peermux ) );
        if ( ! peermux )
                return -ENOMEM;
        ref_init ( &peermux->refcnt, peermux_free );
        intf_init ( &peermux->xfer, &peermux_xfer_desc, &peermux->refcnt );
        intf_init ( &peermux->info, &peermux_info_desc, &peermux->refcnt );
        peermux->uri = uri_get ( uri );
        xferbuf_umalloc_init ( &peermux->buffer );
        process_init_stopped ( &peermux->process, &peermux_process_desc,
                               &peermux->refcnt );
        INIT_LIST_HEAD ( &peermux->busy );
        INIT_LIST_HEAD ( &peermux->idle );
        for ( i = 0 ; i < PEERMUX_MAX_BLOCKS ; i++ ) {
                peermblk = &peermux->block[i];
                peermblk->peermux = peermux;
                list_add_tail ( &peermblk->list, &peermux->idle );
                intf_init ( &peermblk->xfer, &peermux_block_desc,
                            &peermux->refcnt );
        }

        /* Attach to parent interfaces, mortalise self, and return */
        intf_plug_plug ( &peermux->xfer, xfer );
        intf_plug_plug ( &peermux->info, info );
        ref_put ( &peermux->refcnt );
        return 0;
}