Não pode escolher mais do que 25 tópicos
Os tópicos devem começar com uma letra ou um número, podem incluir traços ('-') e podem ter até 35 caracteres.
249 linhas
8.2 KiB
249 linhas
8.2 KiB
#pragma once
|
|
|
|
#pragma once
|
|
|
|
#ifdef __cplusplus
|
|
#include <cstdint>
|
|
#include <cstddef>
|
|
#include <iterator>
|
|
|
|
#else
|
|
#include <stdint.h>
|
|
#include <stddef.h>
|
|
#endif
|
|
|
|
|
|
struct sl_log_transaction;
|
|
struct sl_log_transaction_internals;
|
|
|
|
#ifdef __cplusplus
|
|
namespace sl {
|
|
using cstyle_log_transaction = sl_log_transaction;
|
|
using cstyle_log_transaction_internals = sl_log_transaction_internals;
|
|
|
|
/**
|
|
* @brief This class represents a logging transaction
|
|
* @details
|
|
* This class has the following guarantees:
|
|
* - Can be built on the stack safely
|
|
* - This class never allocates using the system allocator
|
|
* - This class does not perform any system call
|
|
* - Finalization cannot happen twice from the public interface
|
|
* - This class may pad the log by up to <tt>std::hardware_destructive_interference</tt> bytes
|
|
* - This class is both thread-safe and multiprocessing-safe to finalize
|
|
*
|
|
* @details
|
|
* This class expects the finalization to occur in the same thread that wrote any data to the log.
|
|
* @pre
|
|
* This class expects the logging buffer to be at least 2 binary orders of magnitude bigger than the largest log
|
|
* message. It is recommended that it is at least 6 binary orders of magnitude bigger than the largest log.
|
|
* @post
|
|
* This class leaves the log in a valid state in accordance to the defined log strategies.
|
|
*/
|
|
class log_transaction final {
|
|
char* local_start;
|
|
size_t local_size;
|
|
char* buffer_start;
|
|
size_t buffer_size;
|
|
void* buffer_initiator_page;
|
|
bool is_finalized = false;
|
|
|
|
void finalize_impl();
|
|
|
|
/**
|
|
* @brief A forward iterator to the current log transaction.
|
|
*/
|
|
class iterator final {
|
|
using iterator_category = std::forward_iterator_tag;
|
|
using difference_type = std::ptrdiff_t;
|
|
using value_type = char;
|
|
using pointer = char*;
|
|
using reference = char&;
|
|
|
|
log_transaction& owner_ref;
|
|
size_t index;
|
|
public:
|
|
explicit iterator(log_transaction& parent, size_t position = 0)
|
|
: owner_ref(parent)
|
|
, index(((parent.buffer_start - parent.local_start) + position)%parent.buffer_size)
|
|
{}
|
|
iterator& operator++() {
|
|
index+=1;
|
|
index%=owner_ref.buffer_size;
|
|
return *this;
|
|
}
|
|
iterator operator++(int) {
|
|
auto cpy = *this;
|
|
index+=1;
|
|
index%=owner_ref.buffer_size;
|
|
return cpy;
|
|
}
|
|
difference_type operator-(iterator other) const {
|
|
size_t forward, backward;
|
|
forward = owner_ref.buffer_size - index;
|
|
forward += other.index;
|
|
backward = other.index - index;
|
|
return static_cast<difference_type>(std::min(forward, backward));
|
|
}
|
|
reference operator*() {
|
|
return owner_ref.buffer_start[index];
|
|
}
|
|
};
|
|
public:
|
|
/**
|
|
* @brief Starts a transaction. You have to then write your logs between the start and the end of the
|
|
* transaction, then finalize it.
|
|
* @details
|
|
* Guarantees are as follow:
|
|
* - This constructor never allocates using the system allocator
|
|
* - This constructor does not perform any system call
|
|
* - This constructor may pad the log by up to <tt>std::hardware_destructive_interference</tt> bytes
|
|
* - This constructor is both thread-safe and multiprocessing-safe
|
|
*
|
|
* @pre
|
|
* We expect the provided <tt>internal_id</tt> to be valid and registered, if it is not, the transaction may look for a
|
|
* log named "UNHANDLED_ERRORS" and log there instead silently.
|
|
* @post
|
|
* A started transaction MUST be finalized. The log can, upon initiation of the transaction, no longer be
|
|
* pushed to its sink past the current sequence point of the transaction.
|
|
*
|
|
* @post
|
|
* This class will finalize an un-finalized transaction
|
|
* @param internal_id the logger id where the transaction is to happen
|
|
* @param log_size the amount of bytes to write in the transaction.
|
|
*/
|
|
explicit log_transaction(int internal_id, size_t log_size);
|
|
|
|
log_transaction(const log_transaction&) = delete;
|
|
log_transaction(log_transaction&&) = delete;
|
|
void operator=(const log_transaction&) = delete;
|
|
void operator=(log_transaction&&) = delete;
|
|
|
|
/**
|
|
* @brief Unsafely accesses the underlying buffer
|
|
* @param index The index to the buffer to access
|
|
* @return a reference to an underlying <tt>char</tt>, undefined behaviour is the index is invalid
|
|
*/
|
|
char& operator[](size_t index) {
|
|
return buffer_start[((buffer_start - local_start) + index)%buffer_size];
|
|
}
|
|
|
|
/**
|
|
* @brief Obtains a forward iterator to the start of the writable range
|
|
* @return a non-descript iterator to the beginning of the range
|
|
*/
|
|
iterator begin() {
|
|
return iterator(*this, 0);
|
|
}
|
|
|
|
/**
|
|
* @brief Obtains a forward iterator to the end of the writable range
|
|
* @return a non-descript iterator to one-past-the-end of the range
|
|
*/
|
|
iterator end() {
|
|
return iterator(*this, local_size);
|
|
}
|
|
|
|
/**
|
|
* @brief Finalizes the transaction
|
|
* @details
|
|
* Finalizes a transaction, makes access to the finalized buffer undefined behaviour. If <tt>NDEBUG</tt> is
|
|
* defined, accesses will lead to a near-nullptr dereference.
|
|
*
|
|
* @details
|
|
* You are NOT protected against erroneous double finalization in debug mode. You are protected against double
|
|
* finalization out of debug mode. This protection and these erroneous states do not interact with the
|
|
* destructor, which will finalize transactions if not finalized yet.
|
|
*/
|
|
void finalize();
|
|
|
|
/**
|
|
* @see{void finalize()}
|
|
*/
|
|
~log_transaction(){
|
|
if(!is_finalized) finalize_impl();
|
|
}
|
|
};
|
|
}
|
|
|
|
#else
|
|
typedef struct sl_log_transaction log_transaction;
|
|
typedef struct sl_log_transaction_internals log_transaction_internals;
|
|
#endif
|
|
|
|
/**
|
|
* @brief Represents a transaction in the log. Must be finalized for proper operation of the log.
|
|
*/
|
|
struct sl_log_transaction {
|
|
char* begin; /**< The start of the given writable span */
|
|
char* end; /**< 1 element past the end of the writable span */
|
|
|
|
/**
|
|
* @brief Internal, do not touch
|
|
* @internal this is a pointer to a registry_slab, hence the need for reference stability/pointer stability
|
|
*/
|
|
sl_log_transaction_internals* internals;
|
|
};
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
/**
|
|
* @brief Starts a transaction. You have to then write your logs between the start and the end of the transaction,
|
|
* then finalize it.
|
|
* @details
|
|
* Guarantees are as follow:
|
|
* - This function never allocates using the system allocator
|
|
* - This function does not perform any system call
|
|
* - This function may need to pad the log to be operable by C easily
|
|
* - This function is both thread-safe and multiprocessing-safe
|
|
*
|
|
* @pre
|
|
* We expect the provided internal_id to be valid and registered, if it is not, the transaction may look for a log
|
|
* named "UNHANDLED_ERRORS" and log there instead silently.
|
|
* @post
|
|
* A started transaction MUST be finalized. The log can, upon initiation of the transaction, no longer be pushed to
|
|
* its sink past the current sequence point of the transaction.
|
|
* @param internal_id the logger id where the transaction is to happen
|
|
* @param log_size the amount of bytes to write in the transaction.
|
|
* @return a transaction of at least log_size bytes
|
|
*/
|
|
sl_log_transaction sl_start_log_transaction(int internal_id, size_t log_size);
|
|
|
|
/**
|
|
* @brief Finalizes a transaction.
|
|
* @details
|
|
* Be cautious. Finalizing a finalized transaction should NEVER be done. It may wait forever, screw up your log, and
|
|
* clog your log queue forever.
|
|
* @pre
|
|
* The transaction to finalize must never have been finalized before. If it has been finalized before, the
|
|
* finalization may never terminate.
|
|
* @post
|
|
* All data written in the transaction is thenceforth scheduled to be written. The transaction state is now moot
|
|
* and should not be accessed further, and should possibly be cleared.
|
|
* @param target the transaction to finalize.
|
|
*/
|
|
void sl_finalize_log_transaction(sl_log_transaction target);
|
|
|
|
/**
|
|
* @brief Clears a transaction object. This is not required but may help prevent bugs.
|
|
* @param to_clear
|
|
*/
|
|
inline void sl_clear_transaction(sl_log_transaction* to_clear) {
|
|
#ifdef NDEBUG
|
|
do {} while(false);
|
|
#else
|
|
#ifdef __cplusplus
|
|
to_clear->begin = nullptr;
|
|
to_clear->end = nullptr;
|
|
to_clear->internals = nullptr;
|
|
#else
|
|
to_clear->begin = NULL;
|
|
to_clear->end = NULL;
|
|
to_clear->internals = NULL;
|
|
#endif
|
|
#endif
|
|
}
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|