92 lines
2.6 KiB
C++
92 lines
2.6 KiB
C++
/**
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* =========================================================================
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* File : trace.h
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* Project : 0 A.D.
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* Description : allows recording and 'playing back' a sequence of
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* : I/Os - useful for benchmarking and archive builder.
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* =========================================================================
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*/
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// license: GPL; see lib/license.txt
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#ifndef INCLUDED_TRACE
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#define INCLUDED_TRACE
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namespace ERR
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{
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const LibError TRACE_EMPTY = -110500;
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}
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extern void trace_enable(bool want_enabled);
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extern void trace_shutdown();
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extern void trace_notify_io(const char* P_fn, size_t size, uint flags);
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extern void trace_notify_free(const char* P_fn, size_t size);
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// TraceEntry operation type.
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// note: rather than only a list of accessed files, we also need to
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// know the application's behavior WRT caching (e.g. when it releases
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// cached buffers). this is necessary so that our simulation can
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// yield the same behavior.
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enum TraceOp
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{
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TO_IO,
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TO_FREE,
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};
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// stores one event that is relevant for file IO / caching.
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//
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// size-optimized a bit since these are all kept in memory
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// (to prevent trace file writes from affecting other IOs)
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struct TraceEntry
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{
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// note: float instead of double for nice 16 byte struct size
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float timestamp; // returned by get_time before operation starts
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const char* atom_fn; // path+name of affected file
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// rationale: store size in the trace because other applications
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// that use this trace format but not our IO code wouldn't know
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// size (since they cannot retrieve the file info given atom_fn).
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size_t size; // of IO (usually the entire file)
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uint op : 8; // operation - see TraceOp
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uint flags : 24; // misc, e.g. file_io flags.
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};
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struct TraceRun
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{
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const TraceEntry* ents;
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size_t num_ents;
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};
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struct Trace
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{
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// most recent first! (see rationale in source)
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const TraceRun* runs;
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size_t num_runs;
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size_t total_ents;
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};
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extern void trace_get(Trace* t);
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extern LibError trace_write_to_file(const char* trace_filename);
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extern LibError trace_read_from_file(const char* trace_filename, Trace* t);
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extern void trace_gen_random(size_t num_entries);
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// simulate carrying out the entry's TraceOp to determine
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// whether this IO would be satisfied by the file_buf cache.
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extern bool trace_entry_causes_io(const TraceEntry* ent);
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enum TraceRunFlags
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{
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TRF_SYNC_TO_TIMESTAMP = 1
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};
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// carry out all operations specified in the trace.
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// if flags&TRF_SYNC_TO_TIMESTAMP, waits until timestamp for each event is
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// reached; otherwise, they are run as fast as possible.
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extern LibError trace_run(const char* trace_filename, uint flags = 0);
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#endif // #ifndef INCLUDED_TRACE
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