288 lines
8.1 KiB
Go
288 lines
8.1 KiB
Go
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// Copyright (C) 2019 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
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//
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// Use of this source code is governed by an MIT-style
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// license that can be found in the LICENSE file.
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// +build sqlite_trace trace
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package sqlite3
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/*
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#ifndef USE_LIBSQLITE3
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#include "sqlite3-binding.h"
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#else
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#include <sqlite3.h>
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#endif
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#include <stdlib.h>
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int traceCallbackTrampoline(unsigned int traceEventCode, void *ctx, void *p, void *x);
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*/
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import "C"
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import (
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"fmt"
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"strings"
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"sync"
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"unsafe"
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)
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// Trace... constants identify the possible events causing callback invocation.
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// Values are same as the corresponding SQLite Trace Event Codes.
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const (
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TraceStmt = uint32(C.SQLITE_TRACE_STMT)
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TraceProfile = uint32(C.SQLITE_TRACE_PROFILE)
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TraceRow = uint32(C.SQLITE_TRACE_ROW)
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TraceClose = uint32(C.SQLITE_TRACE_CLOSE)
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)
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type TraceInfo struct {
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// Pack together the shorter fields, to keep the struct smaller.
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// On a 64-bit machine there would be padding
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// between EventCode and ConnHandle; having AutoCommit here is "free":
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EventCode uint32
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AutoCommit bool
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ConnHandle uintptr
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// Usually filled, unless EventCode = TraceClose = SQLITE_TRACE_CLOSE:
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// identifier for a prepared statement:
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StmtHandle uintptr
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// Two strings filled when EventCode = TraceStmt = SQLITE_TRACE_STMT:
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// (1) either the unexpanded SQL text of the prepared statement, or
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// an SQL comment that indicates the invocation of a trigger;
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// (2) expanded SQL, if requested and if (1) is not an SQL comment.
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StmtOrTrigger string
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ExpandedSQL string // only if requested (TraceConfig.WantExpandedSQL = true)
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// filled when EventCode = TraceProfile = SQLITE_TRACE_PROFILE:
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// estimated number of nanoseconds that the prepared statement took to run:
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RunTimeNanosec int64
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DBError Error
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}
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// TraceUserCallback gives the signature for a trace function
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// provided by the user (Go application programmer).
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// SQLite 3.14 documentation (as of September 2, 2016)
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// for SQL Trace Hook = sqlite3_trace_v2():
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// The integer return value from the callback is currently ignored,
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// though this may change in future releases. Callback implementations
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// should return zero to ensure future compatibility.
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type TraceUserCallback func(TraceInfo) int
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type TraceConfig struct {
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Callback TraceUserCallback
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EventMask uint32
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WantExpandedSQL bool
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}
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func fillDBError(dbErr *Error, db *C.sqlite3) {
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// See SQLiteConn.lastError(), in file 'sqlite3.go' at the time of writing (Sept 5, 2016)
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dbErr.Code = ErrNo(C.sqlite3_errcode(db))
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dbErr.ExtendedCode = ErrNoExtended(C.sqlite3_extended_errcode(db))
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dbErr.err = C.GoString(C.sqlite3_errmsg(db))
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}
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func fillExpandedSQL(info *TraceInfo, db *C.sqlite3, pStmt unsafe.Pointer) {
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if pStmt == nil {
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panic("No SQLite statement pointer in P arg of trace_v2 callback")
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}
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expSQLiteCStr := C.sqlite3_expanded_sql((*C.sqlite3_stmt)(pStmt))
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defer C.sqlite3_free(unsafe.Pointer(expSQLiteCStr))
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if expSQLiteCStr == nil {
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fillDBError(&info.DBError, db)
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return
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}
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info.ExpandedSQL = C.GoString(expSQLiteCStr)
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}
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//export traceCallbackTrampoline
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func traceCallbackTrampoline(
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traceEventCode C.uint,
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// Parameter named 'C' in SQLite docs = Context given at registration:
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ctx unsafe.Pointer,
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// Parameter named 'P' in SQLite docs (Primary event data?):
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p unsafe.Pointer,
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// Parameter named 'X' in SQLite docs (eXtra event data?):
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xValue unsafe.Pointer) C.int {
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eventCode := uint32(traceEventCode)
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if ctx == nil {
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panic(fmt.Sprintf("No context (ev 0x%x)", traceEventCode))
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}
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contextDB := (*C.sqlite3)(ctx)
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connHandle := uintptr(ctx)
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var traceConf TraceConfig
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var found bool
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if eventCode == TraceClose {
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// clean up traceMap: 'pop' means get and delete
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traceConf, found = popTraceMapping(connHandle)
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} else {
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traceConf, found = lookupTraceMapping(connHandle)
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}
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if !found {
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panic(fmt.Sprintf("Mapping not found for handle 0x%x (ev 0x%x)",
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connHandle, eventCode))
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}
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var info TraceInfo
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info.EventCode = eventCode
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info.AutoCommit = (int(C.sqlite3_get_autocommit(contextDB)) != 0)
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info.ConnHandle = connHandle
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switch eventCode {
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case TraceStmt:
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info.StmtHandle = uintptr(p)
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var xStr string
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if xValue != nil {
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xStr = C.GoString((*C.char)(xValue))
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}
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info.StmtOrTrigger = xStr
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if !strings.HasPrefix(xStr, "--") {
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// Not SQL comment, therefore the current event
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// is not related to a trigger.
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// The user might want to receive the expanded SQL;
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// let's check:
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if traceConf.WantExpandedSQL {
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fillExpandedSQL(&info, contextDB, p)
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}
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}
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case TraceProfile:
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info.StmtHandle = uintptr(p)
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if xValue == nil {
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panic("NULL pointer in X arg of trace_v2 callback for SQLITE_TRACE_PROFILE event")
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}
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info.RunTimeNanosec = *(*int64)(xValue)
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// sample the error //TODO: is it safe? is it useful?
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fillDBError(&info.DBError, contextDB)
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case TraceRow:
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info.StmtHandle = uintptr(p)
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case TraceClose:
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handle := uintptr(p)
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if handle != info.ConnHandle {
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panic(fmt.Sprintf("Different conn handle 0x%x (expected 0x%x) in SQLITE_TRACE_CLOSE event.",
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handle, info.ConnHandle))
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}
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default:
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// Pass unsupported events to the user callback (if configured);
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// let the user callback decide whether to panic or ignore them.
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}
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// Do not execute user callback when the event was not requested by user!
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// Remember that the Close event is always selected when
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// registering this callback trampoline with SQLite --- for cleanup.
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// In the future there may be more events forced to "selected" in SQLite
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// for the driver's needs.
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if traceConf.EventMask&eventCode == 0 {
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return 0
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}
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r := 0
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if traceConf.Callback != nil {
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r = traceConf.Callback(info)
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}
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return C.int(r)
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}
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type traceMapEntry struct {
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config TraceConfig
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}
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var traceMapLock sync.Mutex
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var traceMap = make(map[uintptr]traceMapEntry)
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func addTraceMapping(connHandle uintptr, traceConf TraceConfig) {
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traceMapLock.Lock()
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defer traceMapLock.Unlock()
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oldEntryCopy, found := traceMap[connHandle]
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if found {
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panic(fmt.Sprintf("Adding trace config %v: handle 0x%x already registered (%v).",
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traceConf, connHandle, oldEntryCopy.config))
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}
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traceMap[connHandle] = traceMapEntry{config: traceConf}
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}
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func lookupTraceMapping(connHandle uintptr) (TraceConfig, bool) {
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traceMapLock.Lock()
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defer traceMapLock.Unlock()
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entryCopy, found := traceMap[connHandle]
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return entryCopy.config, found
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}
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// 'pop' = get and delete from map before returning the value to the caller
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func popTraceMapping(connHandle uintptr) (TraceConfig, bool) {
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traceMapLock.Lock()
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defer traceMapLock.Unlock()
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entryCopy, found := traceMap[connHandle]
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if found {
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delete(traceMap, connHandle)
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}
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return entryCopy.config, found
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}
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// SetTrace installs or removes the trace callback for the given database connection.
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// It's not named 'RegisterTrace' because only one callback can be kept and called.
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// Calling SetTrace a second time on same database connection
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// overrides (cancels) any prior callback and all its settings:
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// event mask, etc.
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func (c *SQLiteConn) SetTrace(requested *TraceConfig) error {
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connHandle := uintptr(unsafe.Pointer(c.db))
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_, _ = popTraceMapping(connHandle)
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if requested == nil {
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// The traceMap entry was deleted already by popTraceMapping():
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// can disable all events now, no need to watch for TraceClose.
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err := c.setSQLiteTrace(0)
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return err
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}
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reqCopy := *requested
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// Disable potentially expensive operations
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// if their result will not be used. We are doing this
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// just in case the caller provided nonsensical input.
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if reqCopy.EventMask&TraceStmt == 0 {
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reqCopy.WantExpandedSQL = false
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}
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addTraceMapping(connHandle, reqCopy)
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// The callback trampoline function does cleanup on Close event,
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// regardless of the presence or absence of the user callback.
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// Therefore it needs the Close event to be selected:
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actualEventMask := uint(reqCopy.EventMask | TraceClose)
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err := c.setSQLiteTrace(actualEventMask)
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return err
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}
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func (c *SQLiteConn) setSQLiteTrace(sqliteEventMask uint) error {
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rv := C.sqlite3_trace_v2(c.db,
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C.uint(sqliteEventMask),
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(*[0]byte)(unsafe.Pointer(C.traceCallbackTrampoline)),
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unsafe.Pointer(c.db)) // Fourth arg is same as first: we are
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// passing the database connection handle as callback context.
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if rv != C.SQLITE_OK {
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return c.lastError()
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}
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return nil
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}
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