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wasmtime/crates/c-api/include/wasmtime/store.h
2023-02-13 17:18:37 +00:00

224 lines
8.1 KiB
C

/**
* \file wasmtime/store.h
*
* Wasmtime definition of a "store".
*/
#ifndef WASMTIME_STORE_H
#define WASMTIME_STORE_H
#include <wasm.h>
#include <wasi.h>
#include <wasmtime/error.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* \typedef wasmtime_store_t
* \brief Convenience alias for #wasmtime_store_t
*
* \struct wasmtime_store
* \brief Storage of WebAssembly objects
*
* A store is the unit of isolation between WebAssembly instances in an
* embedding of Wasmtime. Values in one #wasmtime_store_t cannot flow into
* another #wasmtime_store_t. Stores are cheap to create and cheap to dispose.
* It's expected that one-off stores are common in embeddings.
*
* Objects stored within a #wasmtime_store_t are referenced with integer handles
* rather than interior pointers. This means that most APIs require that the
* store be explicitly passed in, which is done via #wasmtime_context_t. It is
* safe to move a #wasmtime_store_t to any thread at any time. A store generally
* cannot be concurrently used, however.
*/
typedef struct wasmtime_store wasmtime_store_t;
/**
* \typedef wasmtime_context_t
* \brief Convenience alias for #wasmtime_context
*
* \struct wasmtime_context
* \brief An interior pointer into a #wasmtime_store_t which is used as
* "context" for many functions.
*
* This context pointer is used pervasively throught Wasmtime's API. This can be
* acquired from #wasmtime_store_context or #wasmtime_caller_context. The
* context pointer for a store is the same for the entire lifetime of a store,
* so it can safely be stored adjacent to a #wasmtime_store_t itself.
*
* Usage of a #wasmtime_context_t must not outlive the original
* #wasmtime_store_t. Additionally #wasmtime_context_t can only be used in
* situations where it has explicitly been granted access to doing so. For
* example finalizers cannot use #wasmtime_context_t because they are not given
* access to it.
*/
typedef struct wasmtime_context wasmtime_context_t;
/**
* \brief Creates a new store within the specified engine.
*
* \param engine the compilation environment with configuration this store is
* connected to
* \param data user-provided data to store, can later be acquired with
* #wasmtime_context_get_data.
* \param finalizer an optional finalizer for `data`
*
* This function creates a fresh store with the provided configuration settings.
* The returned store must be deleted with #wasmtime_store_delete.
*/
WASM_API_EXTERN wasmtime_store_t *wasmtime_store_new(
wasm_engine_t *engine,
void *data,
void (*finalizer)(void*)
);
/**
* \brief Returns the interior #wasmtime_context_t pointer to this store
*/
WASM_API_EXTERN wasmtime_context_t *wasmtime_store_context(wasmtime_store_t *store);
/**
* \brief Provides limits for a store. Used by hosts to limit resource
* consumption of instances. Use negative value to keep the default value
* for the limit.
*
* \param store store where the limits should be set.
* \param memory_size the maximum number of bytes a linear memory can grow to.
* Growing a linear memory beyond this limit will fail. By default,
* linear memory will not be limited.
* \param table_elements the maximum number of elements in a table.
* Growing a table beyond this limit will fail. By default, table elements
* will not be limited.
* \param instances the maximum number of instances that can be created
* for a Store. Module instantiation will fail if this limit is exceeded.
* This value defaults to 10,000.
* \param tables the maximum number of tables that can be created for a Store.
* Module instantiation will fail if this limit is exceeded. This value
* defaults to 10,000.
* \param memories the maximum number of linear memories that can be created
* for a Store. Instantiation will fail with an error if this limit is exceeded.
* This value defaults to 10,000.
*
* Use any negative value for the parameters that should be kept on
* the default values.
*
* Note that the limits are only used to limit the creation/growth of
* resources in the future, this does not retroactively attempt to apply
* limits to the store.
*/
WASM_API_EXTERN void wasmtime_store_limiter(
wasmtime_store_t *store,
int64_t memory_size,
int64_t table_elements,
int64_t instances,
int64_t tables,
int64_t memories
);
/**
* \brief Deletes a store.
*/
WASM_API_EXTERN void wasmtime_store_delete(wasmtime_store_t *store);
/**
* \brief Returns the user-specified data associated with the specified store
*/
WASM_API_EXTERN void *wasmtime_context_get_data(const wasmtime_context_t* context);
/**
* \brief Overwrites the user-specified data associated with this store.
*
* Note that this does not execute the original finalizer for the provided data,
* and the original finalizer will be executed for the provided data when the
* store is deleted.
*/
WASM_API_EXTERN void wasmtime_context_set_data(wasmtime_context_t* context, void *data);
/**
* \brief Perform garbage collection within the given context.
*
* Garbage collects `externref`s that are used within this store. Any
* `externref`s that are discovered to be unreachable by other code or objects
* will have their finalizers run.
*
* The `context` argument must not be NULL.
*/
WASM_API_EXTERN void wasmtime_context_gc(wasmtime_context_t* context);
/**
* \brief Adds fuel to this context's store for wasm to consume while executing.
*
* For this method to work fuel consumption must be enabled via
* #wasmtime_config_consume_fuel_set. By default a store starts with 0 fuel
* for wasm to execute with (meaning it will immediately trap).
* This function must be called for the store to have
* some fuel to allow WebAssembly to execute.
*
* Note that at this time when fuel is entirely consumed it will cause
* wasm to trap. More usages of fuel are planned for the future.
*
* If fuel is not enabled within this store then an error is returned. If fuel
* is successfully added then NULL is returned.
*/
WASM_API_EXTERN wasmtime_error_t *wasmtime_context_add_fuel(wasmtime_context_t *store, uint64_t fuel);
/**
* \brief Returns the amount of fuel consumed by this context's store execution
* so far.
*
* If fuel consumption is not enabled via #wasmtime_config_consume_fuel_set
* then this function will return false. Otherwise true is returned and the
* fuel parameter is filled in with fuel consuemd so far.
*
* Also note that fuel, if enabled, must be originally configured via
* #wasmtime_context_add_fuel.
*/
WASM_API_EXTERN bool wasmtime_context_fuel_consumed(const wasmtime_context_t *context, uint64_t *fuel);
/**
* \brief Attempt to manually consume fuel from the store.
*
* If fuel consumption is not enabled via #wasmtime_config_consume_fuel_set then
* this function will return an error. Otherwise this will attempt to consume
* the specified amount of `fuel` from the store. If successful the remaining
* amount of fuel is stored into `remaining`. If `fuel` couldn't be consumed
* then an error is returned.
*
* Also note that fuel, if enabled, must be originally configured via
* #wasmtime_context_add_fuel.
*/
WASM_API_EXTERN wasmtime_error_t *wasmtime_context_consume_fuel(wasmtime_context_t *context, uint64_t fuel, uint64_t *remaining);
/**
* \brief Configures WASI state within the specified store.
*
* This function is required if #wasmtime_linker_define_wasi is called. This
* will configure the WASI state for instances defined within this store to the
* configuration specified.
*
* This function does not take ownership of `context` but it does take ownership
* of `wasi`. The caller should no longer use `wasi` after calling this function
* (even if an error is returned).
*/
WASM_API_EXTERN wasmtime_error_t *wasmtime_context_set_wasi(wasmtime_context_t *context, wasi_config_t *wasi);
/**
* \brief Configures the relative deadline at which point WebAssembly code will
* trap.
*
* This function configures the store-local epoch deadline after which point
* WebAssembly code will trap.
*
* See also #wasmtime_config_epoch_interruption_set.
*/
WASM_API_EXTERN void wasmtime_context_set_epoch_deadline(wasmtime_context_t *context, uint64_t ticks_beyond_current);
#ifdef __cplusplus
} // extern "C"
#endif
#endif // WASMTIME_STORE_H