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3a8a18c2ca
This change replaces `void const*` by `uint256 const&` for database fetches. Object hashes are expressed using the `uint256` data type, and are converted to `void *` when calling the `fetch` or `fetchBatch` functions. However, in these fetch functions they are converted back to `uint256`, making the conversion process unnecessary. In a few cases the underlying pointer is needed, but that can then be easy obtained via `[hash variable].data()`.
145 lines
4.1 KiB
C++
145 lines
4.1 KiB
C++
#pragma once
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#include <xrpl/nodestore/Types.h>
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#include <cstdint>
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namespace xrpl {
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namespace NodeStore {
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/** A backend used for the NodeStore.
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The NodeStore uses a swappable backend so that other database systems
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can be tried. Different databases may offer various features such
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as improved performance, fault tolerant or distributed storage, or
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all in-memory operation.
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A given instance of a backend is fixed to a particular key size.
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*/
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class Backend
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{
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public:
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/** Destroy the backend.
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All open files are closed and flushed. If there are batched writes
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or other tasks scheduled, they will be completed before this call
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returns.
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*/
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virtual ~Backend() = default;
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/** Get the human-readable name of this backend.
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This is used for diagnostic output.
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*/
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virtual std::string
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getName() = 0;
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/** Get the block size for backends that support it
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*/
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virtual std::optional<std::size_t>
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getBlockSize() const
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{
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return std::nullopt;
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}
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/** Open the backend.
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@param createIfMissing Create the database files if necessary.
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This allows the caller to catch exceptions.
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*/
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virtual void
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open(bool createIfMissing = true) = 0;
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/** Returns true is the database is open.
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*/
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virtual bool
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isOpen() = 0;
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/** Open the backend.
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@param createIfMissing Create the database files if necessary.
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@param appType Deterministic appType used to create a backend.
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@param uid Deterministic uid used to create a backend.
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@param salt Deterministic salt used to create a backend.
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@throws std::runtime_error is function is called not for NuDB backend.
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*/
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virtual void
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open(bool createIfMissing, uint64_t appType, uint64_t uid, uint64_t salt)
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{
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Throw<std::runtime_error>(
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"Deterministic appType/uid/salt not supported by backend " + getName());
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}
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/** Close the backend.
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This allows the caller to catch exceptions.
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*/
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virtual void
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close() = 0;
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/** Fetch a single object.
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If the object is not found or an error is encountered, the
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result will indicate the condition.
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@note This will be called concurrently.
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@param hash The hash of the object.
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@param pObject [out] The created object if successful.
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@return The result of the operation.
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*/
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virtual Status
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fetch(uint256 const& hash, std::shared_ptr<NodeObject>* pObject) = 0;
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/** Fetch a batch synchronously. */
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virtual std::pair<std::vector<std::shared_ptr<NodeObject>>, Status>
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fetchBatch(std::vector<uint256> const& hashes) = 0;
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/** Store a single object.
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Depending on the implementation this may happen immediately
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or deferred using a scheduled task.
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@note This will be called concurrently.
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@param object The object to store.
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*/
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virtual void
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store(std::shared_ptr<NodeObject> const& object) = 0;
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/** Store a group of objects.
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@note This function will not be called concurrently with
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itself or @ref store.
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*/
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virtual void
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storeBatch(Batch const& batch) = 0;
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virtual void
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sync() = 0;
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/** Visit every object in the database
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This is usually called during import.
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@note This routine will not be called concurrently with itself
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or other methods.
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@see import
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*/
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virtual void
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for_each(std::function<void(std::shared_ptr<NodeObject>)> f) = 0;
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/** Estimate the number of write operations pending. */
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virtual int
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getWriteLoad() = 0;
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/** Remove contents on disk upon destruction. */
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virtual void
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setDeletePath() = 0;
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/** Perform consistency checks on database.
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*
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* This method is implemented only by NuDBBackend. It is not yet called
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* anywhere, but it might be a good idea to one day call it at startup to
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* avert a crash.
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*/
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virtual void
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verify()
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{
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}
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/** Returns the number of file descriptors the backend expects to need. */
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virtual int
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fdRequired() const = 0;
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};
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} // namespace NodeStore
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} // namespace xrpl
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