aboutsummaryrefslogtreecommitdiffhomepage
path: root/core/routing.c
blob: 284569a2d9155a2bab0407eed8ad292b3b3573db (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
#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
	//FIXME this might lead to one channel being mentioned multiple times in an apply call
	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;
	}
}