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diff --git a/www/session/sqlite3changegroup_add_strm.html b/www/session/sqlite3changegroup_add_strm.html new file mode 100644 index 0000000..0d04941 --- /dev/null +++ b/www/session/sqlite3changegroup_add_strm.html @@ -0,0 +1,291 @@ +<!DOCTYPE html> +<html><head> +<meta name="viewport" content="width=device-width, initial-scale=1.0"> +<meta http-equiv="content-type" content="text/html; charset=UTF-8"> +<link href="../sqlite.css" rel="stylesheet"> +<title>Streaming Versions of API functions.</title> +<!-- path=../ --> +</head> +<body> +<div class=nosearch> +<a href="../index.html"> +<img class="logo" src="../images/sqlite370_banner.gif" alt="SQLite" border="0"> +</a> +<div><!-- IE hack to prevent disappearing logo --></div> +<div class="tagline desktoponly"> +Small. Fast. Reliable.<br>Choose any three. +</div> +<div class="menu mainmenu"> +<ul> +<li><a href="../index.html">Home</a> +<li class='mobileonly'><a href="javascript:void(0)" onclick='toggle_div("submenu")'>Menu</a> +<li class='wideonly'><a href='../about.html'>About</a> +<li class='desktoponly'><a href="../docs.html">Documentation</a> +<li class='desktoponly'><a href="../download.html">Download</a> +<li class='wideonly'><a href='../copyright.html'>License</a> +<li class='desktoponly'><a href="../support.html">Support</a> +<li class='desktoponly'><a href="../prosupport.html">Purchase</a> +<li class='search' id='search_menubutton'> +<a href="javascript:void(0)" onclick='toggle_search()'>Search</a> +</ul> +</div> +<div class="menu submenu" id="submenu"> +<ul> +<li><a href='../about.html'>About</a> +<li><a href='../docs.html'>Documentation</a> +<li><a href='../download.html'>Download</a> +<li><a href='../support.html'>Support</a> +<li><a href='../prosupport.html'>Purchase</a> +</ul> +</div> +<div class="searchmenu" id="searchmenu"> +<form method="GET" action="../search"> +<select name="s" id="searchtype"> +<option value="d">Search Documentation</option> +<option value="c">Search Changelog</option> +</select> +<input type="text" name="q" id="searchbox" value=""> +<input type="submit" value="Go"> +</form> +</div> +</div> +<script> +function toggle_div(nm) { +var w = document.getElementById(nm); +if( w.style.display=="block" ){ +w.style.display = "none"; +}else{ +w.style.display = "block"; +} +} +function toggle_search() { +var w = document.getElementById("searchmenu"); +if( w.style.display=="block" ){ +w.style.display = "none"; +} else { +w.style.display = "block"; +setTimeout(function(){ +document.getElementById("searchbox").focus() +}, 30); +} +} +function div_off(nm){document.getElementById(nm).style.display="none";} +window.onbeforeunload = function(e){div_off("submenu");} +/* Disable the Search feature if we are not operating from CGI, since */ +/* Search is accomplished using CGI and will not work without it. */ +if( !location.origin || !location.origin.match || !location.origin.match(/http/) ){ +document.getElementById("search_menubutton").style.display = "none"; +} +/* Used by the Hide/Show button beside syntax diagrams, to toggle the */ +function hideorshow(btn,obj){ +var x = document.getElementById(obj); +var b = document.getElementById(btn); +if( x.style.display!='none' ){ +x.style.display = 'none'; +b.innerHTML='show'; +}else{ +x.style.display = ''; +b.innerHTML='hide'; +} +return false; +} +var antiRobot = 0; +function antiRobotGo(){ +if( antiRobot!=3 ) return; +antiRobot = 7; +var j = document.getElementById("mtimelink"); +if(j && j.hasAttribute("data-href")) j.href=j.getAttribute("data-href"); +} +function antiRobotDefense(){ +document.body.onmousedown=function(){ +antiRobot |= 2; +antiRobotGo(); +document.body.onmousedown=null; +} +document.body.onmousemove=function(){ +antiRobot |= 2; +antiRobotGo(); +document.body.onmousemove=null; +} +setTimeout(function(){ +antiRobot |= 1; +antiRobotGo(); +}, 100) +antiRobotGo(); +} +antiRobotDefense(); +</script> +<a href="intro.html"><h2>Session Module C Interface</h2></a><h2>Streaming Versions of API functions.</h2><blockquote><pre>int sqlite3changeset_apply_strm( + sqlite3 *db, /* Apply change to "main" db of this handle */ + int (*xInput)(void *pIn, void *pData, int *pnData), /* Input function */ + void *pIn, /* First arg for xInput */ + int(*xFilter)( + void *pCtx, /* Copy of sixth arg to _apply() */ + const char *zTab /* Table name */ + ), + int(*xConflict)( + void *pCtx, /* Copy of sixth arg to _apply() */ + int eConflict, /* DATA, MISSING, CONFLICT, CONSTRAINT */ + sqlite3_changeset_iter *p /* Handle describing change and conflict */ + ), + void *pCtx /* First argument passed to xConflict */ +); +int sqlite3changeset_apply_v2_strm( + sqlite3 *db, /* Apply change to "main" db of this handle */ + int (*xInput)(void *pIn, void *pData, int *pnData), /* Input function */ + void *pIn, /* First arg for xInput */ + int(*xFilter)( + void *pCtx, /* Copy of sixth arg to _apply() */ + const char *zTab /* Table name */ + ), + int(*xConflict)( + void *pCtx, /* Copy of sixth arg to _apply() */ + int eConflict, /* DATA, MISSING, CONFLICT, CONSTRAINT */ + sqlite3_changeset_iter *p /* Handle describing change and conflict */ + ), + void *pCtx, /* First argument passed to xConflict */ + void **ppRebase, int *pnRebase, + int flags +); +int sqlite3changeset_concat_strm( + int (*xInputA)(void *pIn, void *pData, int *pnData), + void *pInA, + int (*xInputB)(void *pIn, void *pData, int *pnData), + void *pInB, + int (*xOutput)(void *pOut, const void *pData, int nData), + void *pOut +); +int sqlite3changeset_invert_strm( + int (*xInput)(void *pIn, void *pData, int *pnData), + void *pIn, + int (*xOutput)(void *pOut, const void *pData, int nData), + void *pOut +); +int sqlite3changeset_start_strm( + sqlite3_changeset_iter **pp, + int (*xInput)(void *pIn, void *pData, int *pnData), + void *pIn +); +int sqlite3changeset_start_v2_strm( + sqlite3_changeset_iter **pp, + int (*xInput)(void *pIn, void *pData, int *pnData), + void *pIn, + int flags +); +int sqlite3session_changeset_strm( + sqlite3_session *pSession, + int (*xOutput)(void *pOut, const void *pData, int nData), + void *pOut +); +int sqlite3session_patchset_strm( + sqlite3_session *pSession, + int (*xOutput)(void *pOut, const void *pData, int nData), + void *pOut +); +int sqlite3changegroup_add_strm(sqlite3_changegroup*, + int (*xInput)(void *pIn, void *pData, int *pnData), + void *pIn +); +int sqlite3changegroup_output_strm(sqlite3_changegroup*, + int (*xOutput)(void *pOut, const void *pData, int nData), + void *pOut +); +int sqlite3rebaser_rebase_strm( + sqlite3_rebaser *pRebaser, + int (*xInput)(void *pIn, void *pData, int *pnData), + void *pIn, + int (*xOutput)(void *pOut, const void *pData, int nData), + void *pOut +); +</pre></blockquote><p> +The six streaming API xxx_strm() functions serve similar purposes to the +corresponding non-streaming API functions:</p> + +<p><table border=1 style="margin-left:8ex;margin-right:8ex"> + <tr><th>Streaming function<th>Non-streaming equivalent</th> + <tr><td>sqlite3changeset_apply_strm<td><a href="../session/sqlite3changeset_apply.html">sqlite3changeset_apply</a> + <tr><td>sqlite3changeset_apply_strm_v2<td><a href="../session/sqlite3changeset_apply.html">sqlite3changeset_apply_v2</a> + <tr><td>sqlite3changeset_concat_strm<td><a href="../session/sqlite3changeset_concat.html">sqlite3changeset_concat</a> + <tr><td>sqlite3changeset_invert_strm<td><a href="../session/sqlite3changeset_invert.html">sqlite3changeset_invert</a> + <tr><td>sqlite3changeset_start_strm<td><a href="../session/sqlite3changeset_start.html">sqlite3changeset_start</a> + <tr><td>sqlite3session_changeset_strm<td><a href="../session/sqlite3session_changeset.html">sqlite3session_changeset</a> + <tr><td>sqlite3session_patchset_strm<td><a href="../session/sqlite3session_patchset.html">sqlite3session_patchset</a> +</table></p> + +<p>Non-streaming functions that accept changesets (or patchsets) as input +require that the entire changeset be stored in a single buffer in memory. +Similarly, those that return a changeset or patchset do so by returning +a pointer to a single large buffer allocated using sqlite3_malloc(). +Normally this is convenient. However, if an application running in a +low-memory environment is required to handle very large changesets, the +large contiguous memory allocations required can become onerous.</p> + +<p>In order to avoid this problem, instead of a single large buffer, input +is passed to a streaming API functions by way of a callback function that +the sessions module invokes to incrementally request input data as it is +required. In all cases, a pair of API function parameters such as</p> + +<p> <pre> + int nChangeset, + void *pChangeset, + </pre></p> + +<p>Is replaced by:</p> + +<p> <pre> + int (*xInput)(void *pIn, void *pData, int *pnData), + void *pIn, + </pre></p> + +<p>Each time the xInput callback is invoked by the sessions module, the first +argument passed is a copy of the supplied pIn context pointer. The second +argument, pData, points to a buffer (*pnData) bytes in size. Assuming no +error occurs the xInput method should copy up to (*pnData) bytes of data +into the buffer and set (*pnData) to the actual number of bytes copied +before returning SQLITE_OK. If the input is completely exhausted, (*pnData) +should be set to zero to indicate this. Or, if an error occurs, an SQLite +error code should be returned. In all cases, if an xInput callback returns +an error, all processing is abandoned and the streaming API function +returns a copy of the error code to the caller.</p> + +<p>In the case of sqlite3changeset_start_strm(), the xInput callback may be +invoked by the sessions module at any point during the lifetime of the +iterator. If such an xInput callback returns an error, the iterator enters +an error state, whereby all subsequent calls to iterator functions +immediately fail with the same error code as returned by xInput.</p> + +<p>Similarly, streaming API functions that return changesets (or patchsets) +return them in chunks by way of a callback function instead of via a +pointer to a single large buffer. In this case, a pair of parameters such +as:</p> + +<p> <pre> + int *pnChangeset, + void **ppChangeset, + </pre></p> + +<p>Is replaced by:</p> + +<p> <pre> + int (*xOutput)(void *pOut, const void *pData, int nData), + void *pOut + </pre></p> + +<p>The xOutput callback is invoked zero or more times to return data to +the application. The first parameter passed to each call is a copy of the +pOut pointer supplied by the application. The second parameter, pData, +points to a buffer nData bytes in size containing the chunk of output +data being returned. If the xOutput callback successfully processes the +supplied data, it should return SQLITE_OK to indicate success. Otherwise, +it should return some other SQLite error code. In this case processing +is immediately abandoned and the streaming API function returns a copy +of the xOutput error code to the application.</p> + +<p>The sessions module never invokes an xOutput callback with the third +parameter set to a value less than or equal to zero. Other than this, +no guarantees are made as to the size of the chunks of data returned. +</p><p>See also lists of + <a href="objlist.html">Objects</a>, + <a href="constlist.html">Constants</a>, and + <a href="funclist.html">Functions</a>.</p> + |