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0b5538c300
Trace events outside the global mutex cannot be used with the simple trace backend since it is not thread-safe. There is no check to prevent them being enabled so people sometimes learn this the hard way. This patch restructures the simple trace backend with a ring buffer suitable for multiple concurrent writers. A writeout thread empties the trace buffer when threshold fill levels are reached. Should the writeout thread be unable to keep up with trace generation, records will simply be dropped. Each time events are dropped a special record is written to the trace file indicating how many events were dropped. The event ID is 0xfffffffffffffffe and its signature is dropped(uint32_t count). Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
49 lines
1.5 KiB
C
49 lines
1.5 KiB
C
/*
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* Simple trace backend
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*
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* Copyright IBM, Corp. 2010
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#ifndef SIMPLETRACE_H
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#define SIMPLETRACE_H
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#include <stdint.h>
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#include <stdbool.h>
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#include <stdio.h>
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#ifdef CONFIG_SIMPLE_TRACE
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typedef uint64_t TraceEventID;
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typedef struct {
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const char *tp_name;
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bool state;
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} TraceEvent;
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void trace0(TraceEventID event);
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void trace1(TraceEventID event, uint64_t x1);
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void trace2(TraceEventID event, uint64_t x1, uint64_t x2);
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void trace3(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3);
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void trace4(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4);
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void trace5(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5);
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void trace6(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5, uint64_t x6);
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void st_print_trace(FILE *stream, fprintf_function stream_printf);
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void st_print_trace_events(FILE *stream, fprintf_function stream_printf);
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bool st_change_trace_event_state(const char *tname, bool tstate);
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void st_print_trace_file_status(FILE *stream, fprintf_function stream_printf);
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void st_set_trace_file_enabled(bool enable);
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bool st_set_trace_file(const char *file);
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void st_flush_trace_buffer(void);
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void st_init(const char *file);
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#else
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static inline void st_init(const char *file)
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{
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/* Do nothing */
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}
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#endif /* !CONFIG_SIMPLE_TRACE */
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#endif /* SIMPLETRACE_H */
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