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#include <string.h>
#include <signal.h>
#include <time.h>
#include <errno.h>
#include <unistd.h>
#ifndef _WIN32
#include <sys/select.h>
#define MM_API __attribute__((visibility ("default")))
#else
#define MM_API __attribute__((dllexport))
#endif
#define BACKEND_NAME "core/rt"
#define MM_SWAP_LIMIT 20
#include "midimonster.h"
#include "routing.h"
#include "backend.h"
/* Core-internal structures */
typedef struct /*_event_collection*/ {
size_t alloc;
size_t n;
channel** channel;
channel_value* value;
} event_collection;
typedef struct /*_mm_channel_mapping*/ {
channel* from;
size_t destinations;
channel** to;
} channel_mapping;
static struct {
//routing_hash is set up for 256 buckets
size_t entries[256];
channel_mapping* map[256];
event_collection pool[2];
event_collection* events;
} routing = {
.events = routing.pool
};
static size_t routing_hash(channel* key){
uint64_t repr = (uint64_t) key;
//return 8bit hash for 256 buckets, not ideal but it works
return (repr ^ (repr >> 8) ^ (repr >> 16) ^ (repr >> 24) ^ (repr >> 32)) & 0xFF;
}
int mm_map_channel(channel* from, channel* to){
size_t u, m, bucket = routing_hash(from);
//find existing source mapping
for(u = 0; u < routing.entries[bucket]; u++){
if(routing.map[bucket][u].from == from){
break;
}
}
//create new entry
if(u == routing.entries[bucket]){
routing.map[bucket] = realloc(routing.map[bucket], (routing.entries[bucket] + 1) * sizeof(channel_mapping));
if(!routing.map[bucket]){
routing.entries[bucket] = 0;
LOG("Failed to allocate memory");
return 1;
}
memset(routing.map[bucket] + routing.entries[bucket], 0, sizeof(channel_mapping));
routing.entries[bucket]++;
routing.map[bucket][u].from = from;
}
//check whether the target is already mapped
for(m = 0; m < routing.map[bucket][u].destinations; m++){
if(routing.map[bucket][u].to[m] == to){
return 0;
}
}
//add a mapping target
routing.map[bucket][u].to = realloc(routing.map[bucket][u].to, (routing.map[bucket][u].destinations + 1) * sizeof(channel*));
if(!routing.map[bucket][u].to){
LOG("Failed to allocate memory");
routing.map[bucket][u].destinations = 0;
return 1;
}
routing.map[bucket][u].to[routing.map[bucket][u].destinations] = to;
routing.map[bucket][u].destinations++;
return 0;
}
MM_API int mm_channel_event(channel* c, channel_value v){
size_t u, p, bucket = routing_hash(c);
//find mapped channels
for(u = 0; u < routing.entries[bucket]; u++){
if(routing.map[bucket][u].from == c){
break;
}
}
if(u == routing.entries[bucket]){
//target-only channel
return 0;
}
//resize event structures to fit additional events
if(routing.events->n + routing.map[bucket][u].destinations >= routing.events->alloc){
routing.events->channel = realloc(routing.events->channel, (routing.events->alloc + routing.map[bucket][u].destinations) * sizeof(channel*));
routing.events->value = realloc(routing.events->value, (routing.events->alloc + routing.map[bucket][u].destinations) * sizeof(channel_value));
if(!routing.events->channel || !routing.events->value){
LOG("Failed to allocate memory");
routing.events->alloc = 0;
routing.events->n = 0;
return 1;
}
routing.events->alloc += routing.map[bucket][u].destinations;
}
//enqueue channel events
/*
* This might lead to one channel being mentioned multiple times in an apply call.
* That effect should not be eliminated as there are legitimate uses for one channel
* being set multiple times in one core iteration (e.g. for stateful layer selection messages)
*/
memcpy(routing.events->channel + routing.events->n, routing.map[bucket][u].to, routing.map[bucket][u].destinations * sizeof(channel*));
for(p = 0; p < routing.map[bucket][u].destinations; p++){
routing.events->value[routing.events->n + p] = v;
}
routing.events->n += routing.map[bucket][u].destinations;
return 0;
}
void routing_stats(){
size_t n = 0, u, max = 0;
//count and report mappings
for(u = 0; u < sizeof(routing.map) / sizeof(routing.map[0]); u++){
n += routing.entries[u];
max = max(max, routing.entries[u]);
}
LOGPF("Routing %" PRIsize_t " sources, largest bucket has %" PRIsize_t " entries",
n, max);
}
int routing_iteration(){
event_collection* secondary = NULL;
size_t u, swaps = 0;
//limit number of collector swaps per iteration to prevent complete deadlock
while(routing.events->n && swaps < MM_SWAP_LIMIT){
//swap primary and secondary event collectors
DBGPF("Swapping event collectors, %" PRIsize_t " events in primary", routing.events->n);
for(u = 0; u < sizeof(routing.pool) / sizeof(routing.pool[0]); u++){
if(routing.events != routing.pool + u){
secondary = routing.events;
routing.events = routing.pool + u;
break;
}
}
//push collected events to target backends
if(secondary->n && backends_notify(secondary->n, secondary->channel, secondary->value)){
LOG("Backends failed to handle output");
return 1;
}
//reset the event count
secondary->n = 0;
}
if(swaps == MM_SWAP_LIMIT){
LOG("Iteration swap limit hit, a backend may be configured to route events in an infinite loop");
}
return 0;
}
void routing_cleanup(){
size_t u, n;
for(u = 0; u < sizeof(routing.map) / sizeof(routing.map[0]); u++){
for(n = 0; n < routing.entries[u]; n++){
free(routing.map[u][n].to);
}
free(routing.map[u]);
routing.map[u] = NULL;
routing.entries[u] = 0;
}
for(u = 0; u < sizeof(routing.pool) / sizeof(routing.pool[0]); u++){
free(routing.pool[u].channel);
free(routing.pool[u].value);
routing.pool[u].alloc = 0;
}
}
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