refactor: unify runner lifecycles and weight residency (#1940)

src/core/compute_workspace.h

@@ -0,0 +1,64 @@
+#ifndef __SD_CORE_COMPUTE_WORKSPACE_H__
+#define __SD_CORE_COMPUTE_WORKSPACE_H__
+
+#include <functional>
+#include <vector>
+
+#include "ggml-alloc.h"
+#include "ggml-backend.h"
+
+namespace sd {
+    struct BackendBufferSize {
+        ggml_backend_t backend = nullptr;
+        size_t bytes           = 0;
+    };
+
+    class ComputeWorkspace {
+        ggml_backend_t backend_;
+        std::vector<ggml_backend_t> extra_backends_;
+        ggml_backend_t cpu_backend_     = nullptr;
+        ggml_gallocr_t allocator_       = nullptr;
+        ggml_backend_sched_t scheduler_ = nullptr;
+        size_t scheduler_capacity_      = 0;
+        std::vector<uint64_t> reservation_;
+        bool active_         = false;
+        size_t reservations_ = 0;
+
+        ggml_backend_sched_t make_scheduler(size_t graph_size);
+        bool needs_scheduler(ggml_cgraph* graph) const;
+
+    public:
+        struct Measurement {
+            std::vector<BackendBufferSize> buffers;
+            bool scheduler = false;
+        };
+        using AssignNodes = std::function<void(ggml_backend_sched_t, ggml_cgraph*)>;
+
+        explicit ComputeWorkspace(ggml_backend_t backend)
+            : backend_(backend) {}
+        ~ComputeWorkspace();
+        ComputeWorkspace(const ComputeWorkspace&)            = delete;
+        ComputeWorkspace& operator=(const ComputeWorkspace&) = delete;
+
+        void set_extra_backends(const std::vector<ggml_backend_t>& backends);
+        bool measurement_matches(ggml_cgraph* graph, const Measurement& measurement) const;
+        bool prepare(const Measurement& measurement);
+        bool release_excess(const Measurement& measurement);
+        bool allocate(ggml_cgraph* graph, const AssignNodes& assign_nodes);
+        Measurement measure(
+            ggml_cgraph* graph,
+            size_t direct_bytes,
+            const std::function<ggml_backend_t(const ggml_tensor*)>& external_backend,
+            const AssignNodes& assign_nodes);
+        void synchronize() const;
+        void segment_end();
+        bool release();
+        bool active() const { return active_; }
+        ggml_backend_sched_t scheduler() const { return scheduler_; }
+        ggml_backend_t cpu_backend() const { return cpu_backend_; }
+        size_t bytes(ggml_backend_t backend) const;
+        size_t reservation_count() const { return reservations_; }
+    };
+}
+
+#endif  // __SD_CORE_COMPUTE_WORKSPACE_H__