1 files changed, 447 insertions, 0 deletions
diff --git a/src/cache.c b/src/cache.c
new file mode 100644
index 0000000..4f8ed4e
--- /dev/null
+++ b/src/cache.c
@@ -0,0 +1,447 @@
+/*
+ * This file is part of libplacebo.
+ *
+ * libplacebo is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * libplacebo 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with libplacebo. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <locale.h>
+#include <limits.h>
+
+#include "common.h"
+#include "cache.h"
+#include "log.h"
+#include "pl_thread.h"
+
+const struct pl_cache_params pl_cache_default_params = {0};
+
+struct priv {
+    pl_log log;
+    pl_mutex lock;
+    PL_ARRAY(pl_cache_obj) objects;
+    size_t total_size;
+};
+
+int pl_cache_objects(pl_cache cache)
+{
+    if (!cache)
+        return 0;
+
+    struct priv *p = PL_PRIV(cache);
+    pl_mutex_lock(&p->lock);
+    int num = p->objects.num;
+    pl_mutex_unlock(&p->lock);
+    return num;
+}
+
+size_t pl_cache_size(pl_cache cache)
+{
+    if (!cache)
+        return 0;
+
+    struct priv *p = PL_PRIV(cache);
+    pl_mutex_lock(&p->lock);
+    size_t size = p->total_size;
+    pl_mutex_unlock(&p->lock);
+    return size;
+}
+
+pl_cache pl_cache_create(const struct pl_cache_params *params)
+{
+    struct pl_cache_t *cache = pl_zalloc_obj(NULL, cache, struct priv);
+    struct priv *p = PL_PRIV(cache);
+    pl_mutex_init(&p->lock);
+    if (params) {
+        cache->params = *params;
+        p->log = params->log;
+    }
+
+    // Sanitize size limits
+    size_t total_size  = PL_DEF(cache->params.max_total_size,  SIZE_MAX);
+    size_t object_size = PL_DEF(cache->params.max_object_size, SIZE_MAX);
+    object_size = PL_MIN(total_size, object_size);
+    cache->params.max_total_size  = total_size;
+    cache->params.max_object_size = object_size;
+
+    return cache;
+}
+
+static void remove_obj(pl_cache cache, pl_cache_obj obj)
+{
+    struct priv *p = PL_PRIV(cache);
+
+    p->total_size -= obj.size;
+    if (obj.free)
+        obj.free(obj.data);
+}
+
+void pl_cache_destroy(pl_cache *pcache)
+{
+    pl_cache cache = *pcache;
+    if (!cache)
+         return;
+
+    struct priv *p = PL_PRIV(cache);
+    for (int i = 0; i < p->objects.num; i++)
+        remove_obj(cache, p->objects.elem[i]);
+
+    pl_assert(p->total_size == 0);
+    pl_mutex_destroy(&p->lock);
+    pl_free((void *) cache);
+    *pcache = NULL;
+}
+
+void pl_cache_reset(pl_cache cache)
+{
+    if (!cache)
+        return;
+
+    struct priv *p = PL_PRIV(cache);
+    pl_mutex_lock(&p->lock);
+    for (int i = 0; i < p->objects.num; i++)
+        remove_obj(cache, p->objects.elem[i]);
+    p->objects.num = 0;
+    pl_assert(p->total_size == 0);
+    pl_mutex_unlock(&p->lock);
+}
+
+static bool try_set(pl_cache cache, pl_cache_obj obj)
+{
+    struct priv *p = PL_PRIV(cache);
+
+    // Remove any existing entry with this key
+    for (int i = p->objects.num - 1; i >= 0; i--) {
+        pl_cache_obj prev = p->objects.elem[i];
+        if (prev.key == obj.key) {
+            PL_TRACE(p, "Removing out-of-date object 0x%"PRIx64, prev.key);
+            remove_obj(cache, prev);
+            PL_ARRAY_REMOVE_AT(p->objects, i);
+            break;
+        }
+    }
+
+    if (!obj.size) {
+        PL_TRACE(p, "Deleted object 0x%"PRIx64, obj.key);
+        return true;
+    }
+
+    if (obj.size > cache->params.max_object_size) {
+        PL_DEBUG(p, "Object 0x%"PRIx64" (size %zu) exceeds max size %zu, discarding",
+                 obj.key, obj.size, cache->params.max_object_size);
+        return false;
+    }
+
+    // Make space by deleting old objects
+    while (p->total_size + obj.size > cache->params.max_total_size ||
+           p->objects.num == INT_MAX)
+    {
+        pl_assert(p->objects.num);
+        pl_cache_obj old = p->objects.elem[0];
+        PL_TRACE(p, "Removing object 0x%"PRIx64" (size %zu) to make room",
+                 old.key, old.size);
+        remove_obj(cache, old);
+        PL_ARRAY_REMOVE_AT(p->objects, 0);
+    }
+
+    if (!obj.free) {
+        obj.data = pl_memdup(NULL, obj.data, obj.size);
+        obj.free = pl_free;
+    }
+
+    PL_TRACE(p, "Inserting new object 0x%"PRIx64" (size %zu)", obj.key, obj.size);
+    PL_ARRAY_APPEND((void *) cache, p->objects, obj);
+    p->total_size += obj.size;
+    return true;
+}
+
+static pl_cache_obj strip_obj(pl_cache_obj obj)
+{
+    return (pl_cache_obj) { .key = obj.key };
+}
+
+bool pl_cache_try_set(pl_cache cache, pl_cache_obj *pobj)
+{
+    if (!cache)
+        return false;
+
+    pl_cache_obj obj = *pobj;
+    struct priv *p = PL_PRIV(cache);
+    pl_mutex_lock(&p->lock);
+    bool ok = try_set(cache, obj);
+    pl_mutex_unlock(&p->lock);
+    if (ok) {
+        *pobj = strip_obj(obj); // ownership transfers, clear ptr
+    } else {
+        obj = strip_obj(obj); // ownership remains with caller, clear copy
+    }
+    if (cache->params.set)
+        cache->params.set(cache->params.priv, obj);
+    return ok;
+}
+
+void pl_cache_set(pl_cache cache, pl_cache_obj *obj)
+{
+    if (!pl_cache_try_set(cache, obj)) {
+        if (obj->free)
+            obj->free(obj->data);
+        *obj = (pl_cache_obj) { .key = obj->key };
+    }
+}
+
+static void noop(void *ignored)
+{
+    (void) ignored;
+}
+
+bool pl_cache_get(pl_cache cache, pl_cache_obj *out_obj)
+{
+    const uint64_t key = out_obj->key;
+    if (!cache)
+        goto fail;
+
+    struct priv *p = PL_PRIV(cache);
+    pl_mutex_lock(&p->lock);
+
+    // Search backwards to prioritize recently added entries
+    for (int i = p->objects.num - 1; i >= 0; i--) {
+        pl_cache_obj obj = p->objects.elem[i];
+        if (obj.key == key) {
+            PL_ARRAY_REMOVE_AT(p->objects, i);
+            p->total_size -= obj.size;
+            pl_mutex_unlock(&p->lock);
+            pl_assert(obj.free);
+            *out_obj = obj;
+            return true;
+        }
+    }
+
+    pl_mutex_unlock(&p->lock);
+    if (!cache->params.get)
+        goto fail;
+
+    pl_cache_obj obj = cache->params.get(cache->params.priv, key);
+    if (!obj.size)
+        goto fail;
+
+    // Sanitize object
+    obj.key = key;
+    obj.free = PL_DEF(obj.free, noop);
+    *out_obj = obj;
+    return true;
+
+fail:
+    *out_obj = (pl_cache_obj) { .key = key };
+    return false;
+}
+
+void pl_cache_iterate(pl_cache cache,
+                      void (*cb)(void *priv, pl_cache_obj obj),
+                      void *priv)
+{
+    if (!cache)
+        return;
+
+    struct priv *p = PL_PRIV(cache);
+    pl_mutex_lock(&p->lock);
+    for (int i = 0; i < p->objects.num; i++)
+        cb(priv, p->objects.elem[i]);
+    pl_mutex_unlock(&p->lock);
+}
+
+// --- Saving/loading
+
+#define CACHE_MAGIC   "pl_cache"
+#define CACHE_VERSION 1
+#define PAD_ALIGN(x)  PL_ALIGN2(x, sizeof(uint32_t))
+
+struct __attribute__((__packed__)) cache_header {
+    char     magic[8];
+    uint32_t version;
+    uint32_t num_entries;
+};
+
+struct __attribute__((__packed__)) cache_entry {
+    uint64_t key;
+    uint64_t size;
+    uint64_t hash;
+};
+
+pl_static_assert(sizeof(struct cache_header) % alignof(struct cache_entry) == 0);
+
+int pl_cache_save_ex(pl_cache cache,
+                     void (*write)(void *priv, size_t size, const void *ptr),
+                     void *priv)
+{
+    if (!cache)
+        return 0;
+
+    struct priv *p = PL_PRIV(cache);
+    pl_mutex_lock(&p->lock);
+    pl_clock_t start = pl_clock_now();
+
+    const int num_objects = p->objects.num;
+    const size_t saved_bytes = p->total_size;
+    write(priv, sizeof(struct cache_header), &(struct cache_header) {
+        .magic       = CACHE_MAGIC,
+        .version     = CACHE_VERSION,
+        .num_entries = num_objects,
+    });
+
+    for (int i = 0; i < num_objects; i++) {
+        pl_cache_obj obj = p->objects.elem[i];
+        PL_TRACE(p, "Saving object 0x%"PRIx64" (size %zu)", obj.key, obj.size);
+        write(priv, sizeof(struct cache_entry), &(struct cache_entry) {
+            .key  = obj.key,
+            .size = obj.size,
+            .hash = pl_mem_hash(obj.data, obj.size),
+        });
+        static const uint8_t padding[PAD_ALIGN(1)] = {0};
+        write(priv, obj.size, obj.data);
+        write(priv, PAD_ALIGN(obj.size) - obj.size, padding);
+    }
+
+    pl_mutex_unlock(&p->lock);
+    pl_log_cpu_time(p->log, start, pl_clock_now(), "saving cache");
+    if (num_objects)
+        PL_DEBUG(p, "Saved %d objects, totalling %zu bytes", num_objects, saved_bytes);
+
+    return num_objects;
+}
+
+int pl_cache_load_ex(pl_cache cache,
+                     bool (*read)(void *priv, size_t size, void *ptr),
+                     void *priv)
+{
+    if (!cache)
+        return 0;
+
+    struct priv *p = PL_PRIV(cache);
+    struct cache_header header;
+    if (!read(priv, sizeof(header), &header)) {
+        PL_ERR(p, "Failed loading cache: file seems empty or truncated");
+        return -1;
+    }
+    if (memcmp(header.magic, CACHE_MAGIC, sizeof(header.magic)) != 0) {
+        PL_ERR(p, "Failed loading cache: invalid magic bytes");
+        return -1;
+    }
+    if (header.version != CACHE_VERSION) {
+        PL_INFO(p, "Failed loading cache: wrong version... skipping");
+        return 0;
+    }
+    if (header.num_entries > INT_MAX) {
+        PL_ERR(p, "Failed loading cache: %"PRIu32" entries overflows int",
+               header.num_entries);
+        return 0;
+    }
+
+    int num_loaded = 0;
+    size_t loaded_bytes = 0;
+    pl_mutex_lock(&p->lock);
+    pl_clock_t start = pl_clock_now();
+
+    for (int i = 0; i < header.num_entries; i++) {
+        struct cache_entry entry;
+        if (!read(priv, sizeof(entry), &entry)) {
+            PL_WARN(p, "Cache seems truncated, missing objects.. ignoring rest");
+            goto error;
+        }
+
+        if (entry.size > SIZE_MAX) {
+            PL_WARN(p, "Cache object size %"PRIu64" overflows SIZE_MAX.. "
+                    "suspect broken file, ignoring rest", entry.size);
+            goto error;
+        }
+
+        void *buf = pl_alloc(NULL, PAD_ALIGN(entry.size));
+        if (!read(priv, PAD_ALIGN(entry.size), buf)) {
+            PL_WARN(p, "Cache seems truncated, missing objects.. ignoring rest");
+            pl_free(buf);
+            goto error;
+        }
+
+        uint64_t checksum = pl_mem_hash(buf, entry.size);
+        if (checksum != entry.hash) {
+            PL_WARN(p, "Cache entry seems corrupt, checksum mismatch.. ignoring rest");
+            pl_free(buf);
+            goto error;
+        }
+
+        pl_cache_obj obj = {
+            .key  = entry.key,
+            .size = entry.size,
+            .data = buf,
+            .free = pl_free,
+        };
+
+        PL_TRACE(p, "Loading object 0x%"PRIx64" (size %zu)", obj.key, obj.size);
+        if (try_set(cache, obj)) {
+            num_loaded++;
+            loaded_bytes += entry.size;
+        } else {
+            pl_free(buf);
+        }
+    }
+
+    pl_log_cpu_time(p->log, start, pl_clock_now(), "loading cache");
+    if (num_loaded)
+        PL_DEBUG(p, "Loaded %d objects, totalling %zu bytes", num_loaded, loaded_bytes);
+
+    // fall through
+error:
+    pl_mutex_unlock(&p->lock);
+    return num_loaded;
+}
+
+// Save/load wrappers
+
+struct ptr_ctx {
+    uint8_t *data; // base pointer
+    size_t size;   // total size
+    size_t pos;    // read/write index
+};
+
+static void write_ptr(void *priv, size_t size, const void *ptr)
+{
+    struct ptr_ctx *ctx = priv;
+    size_t end = PL_MIN(ctx->pos + size, ctx->size);
+    if (end > ctx->pos)
+        memcpy(ctx->data + ctx->pos, ptr, end - ctx->pos);
+    ctx->pos += size;
+}
+
+static bool read_ptr(void *priv, size_t size, void *ptr)
+{
+    struct ptr_ctx *ctx = priv;
+    if (ctx->pos + size > ctx->size)
+        return false;
+    memcpy(ptr, ctx->data + ctx->pos, size);
+    ctx->pos += size;
+    return true;
+}
+
+size_t pl_cache_save(pl_cache cache, uint8_t *data, size_t size)
+{
+    struct ptr_ctx ctx = { data, size };
+    pl_cache_save_ex(cache, write_ptr, &ctx);
+    return ctx.pos;
+}
+
+int pl_cache_load(pl_cache cache, const uint8_t *data, size_t size)
+{
+    return pl_cache_load_ex(cache, read_ptr, &(struct ptr_ctx) {
+        .data = (uint8_t *) data,
+        .size = size,
+    });
+}