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Resolve the JS-side corner case reported in [forum:7774b773937cbe0a | forum post 7774b773937cbe0a] by not caching oo1.Stmt.columnCount.

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FossilOrigin-Name: c3d25c3a25e79e01c4ad0cf11f7dc3b0fb1932f3bcd04935a728ef62f7e07cf1
This commit is contained in:
stephan
2023-05-10 21:06:02 +00:00
parent 28f4e7b286
commit 161f742856
5 changed files with 91 additions and 46 deletions
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98
ext/wasm/api/sqlite3-api-oo1.js
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@ -330,10 +330,15 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
- `db`: the DB object which created the statement.
- `columnCount`: the number of result columns in the query, or 0 for
queries which cannot return results.
- `columnCount`: the number of result columns in the query, or 0
for queries which cannot return results. This property is a proxy
for sqlite3_column_count() and its use in loops should be avoided
because of the call overhead associated with that. The
`columnCount` is not cached when the Stmt is created because a
schema change made via a separate db connection between this
statement's preparation and when it is stepped may invalidate it.
- `parameterCount`: the number of bindable paramters in the query.
- `parameterCount`: the number of bindable parameters in the query.
*/
const Stmt = function(){
if(BindTypes!==arguments[2]){
@ -341,7 +346,6 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
}
this.db = arguments[0];
__ptrMap.set(this, arguments[1]);
this.columnCount = capi.sqlite3_column_count(this.pointer);
this.parameterCount = capi.sqlite3_bind_parameter_count(this.pointer);
};
@ -701,18 +705,18 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
with identical names.
- `callback` = a function which gets called for each row of the
result set, but only if that statement has any result
_rows_. The callback's "this" is the options object, noting
that this function synthesizes one if the caller does not pass
one to exec(). The second argument passed to the callback is
always the current Stmt object, as it's needed if the caller
wants to fetch the column names or some such (noting that they
could also be fetched via `this.columnNames`, if the client
provides the `columnNames` option). If the callback returns a
literal `false` (as opposed to any other falsy value, e.g. an
implicit `undefined` return), any ongoing statement-`step()`
iteration stops without an error. The return value of the
callback is otherwise ignored.
result set, but only if that statement has any result rows. The
callback's "this" is the options object, noting that this
function synthesizes one if the caller does not pass one to
exec(). The second argument passed to the callback is always
the current Stmt object, as it's needed if the caller wants to
fetch the column names or some such (noting that they could
also be fetched via `this.columnNames`, if the client provides
the `columnNames` option). If the callback returns a literal
`false` (as opposed to any other falsy value, e.g. an implicit
`undefined` return), any ongoing statement-`step()` iteration
stops without an error. The return value of the callback is
otherwise ignored.
ACHTUNG: The callback MUST NOT modify the Stmt object. Calling
any of the Stmt.get() variants, Stmt.getColumnName(), or
@ -733,7 +737,7 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
A.1) `'array'` (the default) causes the results of
`stmt.get([])` to be passed to the `callback` and/or appended
to `resultRows`
to `resultRows`.
A.2) `'object'` causes the results of
`stmt.get(Object.create(null))` to be passed to the
@ -744,8 +748,8 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
A.3) `'stmt'` causes the current Stmt to be passed to the
callback, but this mode will trigger an exception if
`resultRows` is an array because appending the statement to
the array would be downright unhelpful.
`resultRows` is an array because appending the transient
statement to the array would be downright unhelpful.
B) An integer, indicating a zero-based column in the result
row. Only that one single value will be passed on.
@ -857,14 +861,21 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
bind = null;
}
if(evalFirstResult && stmt.columnCount){
/* Only forward SELECT results for the FIRST query
/* Only forward SELECT-style results for the FIRST query
in the SQL which potentially has them. */
let gotColNames = Array.isArray(
opt.columnNames
/* As reported in
https://sqlite.org/forum/forumpost/7774b773937cbe0a
we need to delay fetching of the column names until
after the first step() (if we step() at all) because
a schema change between the prepare() and step(), via
another connection, may invalidate the column count
and names. */) ? 0 : 1;
evalFirstResult = false;
if(Array.isArray(opt.columnNames)){
stmt.getColumnNames(opt.columnNames);
}
if(arg.cbArg || resultRows){
for(; stmt.step(); stmt._isLocked = false){
if(0===gotColNames++) stmt.getColumnNames(opt.columnNames);
stmt._isLocked = true;
const row = arg.cbArg(stmt);
if(resultRows) resultRows.push(row);
@ -874,6 +885,10 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
}
stmt._isLocked = false;
}
if(0===gotColNames){
/* opt.columnNames was provided but we visited no result rows */
stmt.getColumnNames(opt.columnNames);
}
}else{
stmt.step();
}
@ -1416,7 +1431,6 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
capi.sqlite3_finalize(this.pointer);
__ptrMap.delete(this);
delete this._mayGet;
delete this.columnCount;
delete this.parameterCount;
delete this.db;
delete this._isLocked;
@ -1686,13 +1700,15 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
}
if(Array.isArray(ndx)){
let i = 0;
while(i<this.columnCount){
const n = this.columnCount;
while(i<n){
ndx[i] = this.get(i++);
}
return ndx;
}else if(ndx && 'object'===typeof ndx){
let i = 0;
while(i<this.columnCount){
const n = this.columnCount;
while(i<n){
ndx[capi.sqlite3_column_name(this.pointer,i)] = this.get(i++);
}
return ndx;
@ -1790,16 +1806,17 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
);
},
/**
If this statement potentially has result columns, this
function returns an array of all such names. If passed an
array, it is used as the target and all names are appended
to it. Returns the target array. Throws if this statement
cannot have result columns. This object's columnCount member
holds the number of columns.
If this statement potentially has result columns, this function
returns an array of all such names. If passed an array, it is
used as the target and all names are appended to it. Returns
the target array. Throws if this statement cannot have result
columns. This object's columnCount property holds the number of
columns.
*/
getColumnNames: function(tgt=[]){
affirmColIndex(affirmStmtOpen(this),0);
for(let i = 0; i < this.columnCount; ++i){
const n = this.columnCount;
for(let i = 0; i < n; ++i){
tgt.push(capi.sqlite3_column_name(this.pointer, i));
}
return tgt;
@ -1826,6 +1843,21 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
Object.defineProperty(Stmt.prototype, 'pointer', prop);
Object.defineProperty(DB.prototype, 'pointer', prop);
}
/**
A Stmt's columntCount property is an interceptor for
sqlite3_column_count().
This requires an unfortunate performance hit compared to caching
columnCount when the Stmt is created/prepared (as was done in
SQLite <=3.42.0), but is necessary in order to handle certain
corner cases, as described in
https://sqlite.org/forum/forumpost/7774b773937cbe0a.
*/
Object.defineProperty(Stmt.prototype, 'columnCount', {
enumerable: false,
get: function(){return capi.sqlite3_column_count(this.pointer)},
set: ()=>toss3("The columnCount property is read-only.")
});
/** The OO API's public namespace. */
sqlite3.oo1 = {