Abdelrahman Said
476 lines
13 KiB
C
476 lines
13 KiB
C
// vim:fileencoding=utf-8:foldmethod=marker
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#include "../src/wapp/wapp.h"
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#include <_inttypes.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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wp_intern WpLogger _log = { .name = wpStr8LitRo("dag_man") };
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/* ---------------------------------------------------------------------------
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* Pool allocator (arena-backed, intrusive free list)
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* -------------------------------------------------------------------------*/
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typedef struct PrPoolFreeNode PrPoolFreeNode;
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struct PrPoolFreeNode {
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PrPoolFreeNode *next;
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};
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typedef struct {
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WpAllocator *allocator;
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PrPoolFreeNode *free_head;
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u64 slot_size;
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} PrPool;
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wp_intern void prPoolInit(PrPool *pool, WpAllocator *allocator, u64 slot_size) {
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pool->allocator = allocator;
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pool->free_head = NULL;
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pool->slot_size = slot_size;
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}
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wp_intern void *prPoolAlloc(PrPool *pool) {
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if (pool->free_head) {
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PrPoolFreeNode *node = pool->free_head;
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pool->free_head = node->next;
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return node;
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}
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return wpMemAllocatorAlloc(pool->allocator, pool->slot_size);
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}
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wp_intern void prPoolFree(PrPool *pool, void *slot) {
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if (!slot) { return; }
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PrPoolFreeNode *node = (PrPoolFreeNode *)slot;
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node->next = pool->free_head;
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pool->free_head = node;
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}
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/* ---------------------------------------------------------------------------
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* Graph
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* -------------------------------------------------------------------------*/
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#define INVALID_NODE_INDEX (u64)-1
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#define INVALID_NODE_ID ((PrNodeId){ .index = INVALID_NODE_INDEX, .generation = INVALID_NODE_INDEX })
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typedef enum {
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PR_NODE_TYPE_NONE,
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PR_NODE_TYPE_READ,
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PR_NODE_TYPE_BLUR,
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PR_NODE_TYPE_GRADE,
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COUNT_NODE_TYPES
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} PrNodeType;
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typedef struct {
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u64 index;
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u64 generation;
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} PrNodeId;
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typedef PrNodeId *PrNodeIdArray;
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typedef struct {
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union {
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WpStr8 path;
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f32 blur;
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f32 gain;
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} params;
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PrNodeType type;
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u64 generation;
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u64 next_free;
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} PrNode;
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typedef PrNode *PrNodeArray;
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/* ---------------------------------------------------------------------------
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* Graph Edge/Vertex type
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* If source or target are INVALID_NODE_ID, it should be treated as a vertex.
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* Otherwise, it should be treated as an edge. Think of it like homogeneous
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* coordinates where a vector {0, 0, 0, 0} is treated as a direction, while
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* a vector {0, 0, 0, 1} is treated as a point
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* ---------------------------------------------------------------------------*/
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typedef struct PrEdgeVertex PrEdgeVertex;
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struct PrEdgeVertex {
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PrEdgeVertex *next_forward;
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PrEdgeVertex *next_backward;
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PrNodeId source;
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PrNodeId target;
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};
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typedef PrEdgeVertex *PrEdgeVertexArray;
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typedef struct {
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PrPool vertex_pool;
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PrNodeArray nodes;
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PrEdgeVertexArray vertices;
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u64 capacity;
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u64 max_count_ever;
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u64 count;
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u64 free_head;
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} PrGraph;
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wp_intern b8 prGraphIsStaleId(const PrGraph *graph, PrNodeId id) {
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u64 generation = graph->nodes[id.index].generation;
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return id.generation != generation;
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}
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wp_intern b8 prGraphIsActiveNode(const PrGraph *graph, PrNodeId id) {
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u64 next_free = graph->nodes[id.index].next_free;
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return !prGraphIsStaleId(graph, id) && next_free == INVALID_NODE_INDEX;
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}
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wp_intern PrNodeId prGraphGetNode(const PrGraph *graph, u64 index) {
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return (PrNodeId){ .index = index, .generation = graph->nodes[index].generation };
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}
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wp_intern void prGraphInit(PrGraph *graph, WpAllocator *allocator, u64 capacity) {
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graph->nodes = wpArrayAllocCapacity(PrNode, allocator, capacity, WP_ARRAY_INIT_FILLED);
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graph->vertices = wpArrayAllocCapacity(PrEdgeVertex, allocator, capacity, WP_ARRAY_INIT_FILLED);
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graph->free_head = 0;
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graph->capacity = capacity;
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graph->max_count_ever = 0;
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graph->count = 0;
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if (!graph->nodes || !graph->vertices) {
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graph->capacity = 0;
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return;
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}
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prPoolInit(&graph->vertex_pool, allocator, sizeof(PrEdgeVertex));
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memset(graph->nodes, 0, capacity * sizeof(PrNode));
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memset(graph->vertices, 0, capacity * sizeof(PrEdgeVertex));
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for (u64 i = 0; i < capacity; ++i) {
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graph->nodes[i].next_free = i < capacity - 1 ? i + 1 : INVALID_NODE_INDEX;
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graph->vertices[i].source = graph->vertices[i].target = INVALID_NODE_ID;
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}
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}
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/* ---------------------------------------------------------------------------
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* Kahn's algorithm — topological sort / cycle detection
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*
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* Returns a WpArray of PrNodeId (sorted topologically). If the result count
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* is less than graph->count, the graph contains a cycle.
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* -------------------------------------------------------------------------*/
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wp_intern PrNodeId *prGraphTopologicalSort(PrGraph *graph, const WpAllocator *allocator) {
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if (graph->count == 0) { return NULL; }
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if (!graph->nodes || graph->capacity == 0) { return NULL; }
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PrNodeIdArray result = wpArrayAllocCapacity(PrNodeId, allocator, graph->count, WP_ARRAY_INIT_NONE);
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if (!result) { return NULL; }
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WpAllocator local_arena = wpMemArenaAllocatorInitZero(KiB(16));
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WpU64Array in_degree = wpArrayAllocCapacity(u64, &local_arena, graph->capacity, WP_ARRAY_INIT_FILLED);
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if (!in_degree) { return result; }
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memset(in_degree, 0, wpArrayCapacity(in_degree) * sizeof(u64));
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for (u64 i = 0; i < graph->max_count_ever; i++) {
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PrNodeId id = prGraphGetNode(graph, i);
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if (!prGraphIsActiveNode(graph, id)) { continue; }
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PrEdgeVertex *vertex = &graph->vertices[i];
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PrEdgeVertex *curr = vertex->next_forward;
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while (curr) {
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in_degree[curr->target.index]++;
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curr = curr->next_forward;
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}
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}
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WpQueue queue = wpQueueAlloc(u64, &local_arena, graph->count);
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for (u64 i = 0; i < graph->max_count_ever; i++) {
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PrNodeId id = prGraphGetNode(graph, i);
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if (!prGraphIsActiveNode(graph, id)) { continue; }
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if (in_degree[i] == 0) {
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wpQueuePush(u64, &queue, &i);
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}
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}
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while (queue.count > 0) {
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u64 *node_idx = wpQueuePop(u64, &queue);
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if (!node_idx) { break; }
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PrNodeId id = prGraphGetNode(graph, *node_idx);
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wpArrayAppendCapped(PrNodeId, result, &id);
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PrEdgeVertex *vertex = &graph->vertices[*node_idx];
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PrEdgeVertex *curr = vertex->next_forward;
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while (curr) {
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u64 target_idx = curr->target.index;
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if (in_degree[target_idx] > 0) {
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in_degree[target_idx]--;
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if (in_degree[target_idx] == 0) {
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wpQueuePush(u64, &queue, &target_idx);
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}
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}
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curr = curr->next_forward;
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}
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}
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return result;
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}
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/* --- edge management -------------------------------------------------- */
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wp_intern void _unlinkForward(PrGraph *graph, PrNodeId from, PrEdgeVertex *edge) {
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if (!prGraphIsActiveNode(graph, from)) { return; }
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PrEdgeVertex *src = &graph->vertices[from.index];
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PrEdgeVertex *curr = src->next_forward;
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PrEdgeVertex *prev = NULL;
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while (curr) {
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if (curr == edge) {
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if (prev) {
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prev->next_forward = curr->next_forward;
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} else {
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src->next_forward = curr->next_forward;
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}
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return;
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}
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prev = curr;
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curr = curr->next_forward;
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}
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}
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wp_intern void _unlinkBackward(PrGraph *graph, PrNodeId to, PrEdgeVertex *edge) {
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if (!prGraphIsActiveNode(graph, to)) { return; }
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PrEdgeVertex *dst = &graph->vertices[to.index];
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PrEdgeVertex *curr = dst->next_backward;
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PrEdgeVertex *prev = NULL;
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while (curr) {
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if (curr == edge) {
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if (prev) {
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prev->next_backward = curr->next_backward;
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} else {
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dst->next_backward = curr->next_backward;
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}
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return;
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}
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prev = curr;
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curr = curr->next_backward;
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}
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}
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wp_intern void prGraphAddEdge(PrGraph *graph, PrNodeId from, PrNodeId to) {
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if (!prGraphIsActiveNode(graph, from) || !prGraphIsActiveNode(graph, to)) { return; }
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if (from.index == to.index) { return; }
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PrEdgeVertex *edge = (PrEdgeVertex *)prPoolAlloc(&graph->vertex_pool);
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if (!edge) { return; }
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edge->source = from;
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edge->target = to;
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/* Link into adjacency chains */
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PrEdgeVertex *src = &graph->vertices[from.index];
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PrEdgeVertex *dst = &graph->vertices[to.index];
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edge->next_forward = src->next_forward;
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edge->next_backward = dst->next_backward;
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src->next_forward = edge;
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dst->next_backward = edge;
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/* Check whether the new edge created a cycle */
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WpAllocator scratch = wpMemArenaAllocatorInitZero(KiB(16));
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PrNodeIdArray sorted = prGraphTopologicalSort(graph, &scratch);
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u64 sorted_count = sorted ? wpArrayCount(sorted) : 0;
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if (sorted_count < graph->count) {
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_unlinkForward(graph, from, edge);
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_unlinkBackward(graph, to, edge);
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prPoolFree(&graph->vertex_pool, edge);
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}
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wpMemArenaAllocatorDestroy(&scratch);
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}
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wp_intern PrNodeId prGraphAddNode(PrGraph *graph, PrNodeType type) {
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u64 idx = graph->free_head;
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if (idx == INVALID_NODE_INDEX) { return INVALID_NODE_ID; }
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PrNode *node = &graph->nodes[idx];
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graph->free_head = node->next_free;
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node->next_free = INVALID_NODE_INDEX;
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node->type = type;
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memset(&node->params, 0, sizeof(node->params));
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graph->count++;
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if (idx + 1 > graph->max_count_ever) { graph->max_count_ever = idx + 1; }
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return (PrNodeId){ .index = idx, .generation = node->generation };
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}
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wp_intern void prGraphRemoveNode(PrGraph *graph, PrNodeId id) {
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if (!prGraphIsActiveNode(graph, id)) { return; }
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PrNode *node = &graph->nodes[id.index];
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u64 next_gen = node->generation + 1;
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memset(node, 0, sizeof(PrNode));
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node->generation = next_gen;
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node->next_free = graph->free_head;
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graph->free_head = id.index;
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PrEdgeVertex *vertex = &graph->vertices[id.index];
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if (!(vertex->next_forward) && !(vertex->next_backward)) {
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goto REMOVE_NODE_UNSET_POINTERS;
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}
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PrEdgeVertex *curr = vertex->next_forward;
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while (curr) {
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PrEdgeVertex *next = curr->next_forward;
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_unlinkBackward(graph, curr->target, curr);
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prPoolFree(&graph->vertex_pool, curr);
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curr = next;
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}
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curr = vertex->next_backward;
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while (curr) {
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PrEdgeVertex *trailing = curr->next_backward;
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_unlinkForward(graph, curr->source, curr);
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prPoolFree(&graph->vertex_pool, curr);
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curr = trailing;
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}
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REMOVE_NODE_UNSET_POINTERS:
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vertex->next_forward = vertex->next_backward = NULL;
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graph->count--;
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}
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wp_intern void prGraphDump(const PrGraph *graph) {
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printf("==============INPUTS==============\n");
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for (u64 i = 0; i < graph->max_count_ever; ++i) {
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PrNodeId id = prGraphGetNode(graph, i);
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if (!prGraphIsActiveNode(graph, id)) { continue; }
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PrEdgeVertex *vertex = &graph->vertices[i];
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printf("%" PRIu64 ":", id.index + 1);
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if (!(vertex->next_backward)) {
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printf(" (none)");
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} else {
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PrEdgeVertex *curr = vertex->next_backward;
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while (curr) {
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printf(" %" PRIu64, curr->source.index + 1);
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curr = curr->next_backward;
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}
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}
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printf("\n");
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}
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printf("==============OUTPUTS==============\n");
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for (u64 i = 0; i < graph->max_count_ever; ++i) {
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PrNodeId id = prGraphGetNode(graph, i);
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if (!prGraphIsActiveNode(graph, id)) { continue; }
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PrEdgeVertex *vertex = &graph->vertices[i];
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printf("%" PRIu64 ":", id.index + 1);
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if (!(vertex->next_forward)) {
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printf(" (none)");
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} else {
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PrEdgeVertex *curr = vertex->next_forward;
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while (curr) {
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printf(" %" PRIu64, curr->target.index + 1);
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curr = curr->next_forward;
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}
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}
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printf("\n");
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}
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}
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i32 main(void) {
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WpAllocator arena = wpMemArenaAllocatorInitZero(MiB(16));
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if (wpMemAllocatorInvalid(&arena)) {
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wpLogFatal(&_log, wpStr8Lit("arena init failed"));
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return 1;
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}
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PrGraph graph = {0};
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prGraphInit(&graph, &arena, 128);
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PrNodeId n1 = prGraphAddNode(&graph, PR_NODE_TYPE_READ);
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PrNodeId n2 = prGraphAddNode(&graph, PR_NODE_TYPE_READ);
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PrNodeId n3 = prGraphAddNode(&graph, PR_NODE_TYPE_READ);
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PrNodeId n4 = prGraphAddNode(&graph, PR_NODE_TYPE_READ);
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PrNodeId n5 = prGraphAddNode(&graph, PR_NODE_TYPE_READ);
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prGraphAddEdge(&graph, n1, n2);
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prGraphAddEdge(&graph, n1, n3);
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prGraphAddEdge(&graph, n1, n5);
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prGraphAddEdge(&graph, n2, n4);
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prGraphAddEdge(&graph, n3, n4);
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prGraphAddEdge(&graph, n3, n5);
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prGraphDump(&graph);
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prGraphRemoveNode(&graph, n3);
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printf("\n");
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prGraphDump(&graph);
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PrNodeId n6 = prGraphAddNode(&graph, PR_NODE_TYPE_READ);
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prGraphAddEdge(&graph, n4, n6);
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printf("\n");
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prGraphDump(&graph);
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prGraphRemoveNode(&graph, n5);
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printf("\n");
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prGraphDump(&graph);
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PrNodeId n7 = prGraphAddNode(&graph, PR_NODE_TYPE_READ);
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prGraphAddEdge(&graph, n1, n7);
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prGraphAddEdge(&graph, n2, n7);
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printf("\n");
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prGraphDump(&graph);
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PrNodeId n8 = prGraphAddNode(&graph, PR_NODE_TYPE_READ);
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prGraphAddEdge(&graph, n6, n8);
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prGraphAddEdge(&graph, n7, n8);
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printf("\n");
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prGraphDump(&graph);
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printf("\n=== Try adding cycle 8→1 (should be rejected) ===\n");
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prGraphAddEdge(&graph, n8, n1);
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printf("\n=== Try adding 8→1 again (still rejected) ===\n");
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prGraphAddEdge(&graph, n8, n1);
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printf("\n=== Try adding cycle 7→2 (should be rejected) ===\n\n");
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prGraphAddEdge(&graph, n7, n2);
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prGraphDump(&graph);
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printf("\n=== Topological sort ===\n");
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PrNodeId *sorted = prGraphTopologicalSort(&graph, &arena);
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if (sorted) {
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u64 n = wpArrayCount(sorted);
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printf(" count: %llu / %llu active\n",
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(unsigned long long)n,
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(unsigned long long)graph.count);
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for (u64 i = 0; i < n; i++) {
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printf(" [%llu] idx=%llu gen=%llu\n",
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(unsigned long long)i,
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(unsigned long long)sorted[i].index,
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(unsigned long long)sorted[i].generation);
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}
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}
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wpMemArenaAllocatorDestroy(&arena);
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return 0;
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}
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