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| -rw-r--r-- | ext/wasm/fiddle/fiddle-worker.js | 379 |
1 files changed, 379 insertions, 0 deletions
diff --git a/ext/wasm/fiddle/fiddle-worker.js b/ext/wasm/fiddle/fiddle-worker.js new file mode 100644 index 0000000..a60b79a --- /dev/null +++ b/ext/wasm/fiddle/fiddle-worker.js @@ -0,0 +1,379 @@ +/* + 2022-05-20 + + The author disclaims copyright to this source code. In place of a + legal notice, here is a blessing: + + * May you do good and not evil. + * May you find forgiveness for yourself and forgive others. + * May you share freely, never taking more than you give. + + *********************************************************************** + + This is the JS Worker file for the sqlite3 fiddle app. It loads the + sqlite3 wasm module and offers access to the db via the Worker + message-passing interface. + + Forewarning: this API is still very much Under Construction and + subject to any number of changes as experience reveals what those + need to be. + + Because we can have only a single message handler, as opposed to an + arbitrary number of discrete event listeners like with DOM elements, + we have to define a lower-level message API. Messages abstractly + look like: + + { type: string, data: type-specific value } + + Where 'type' is used for dispatching and 'data' is a + 'type'-dependent value. + + The 'type' values expected by each side of the main/worker + connection vary. The types are described below but subject to + change at any time as this experiment evolves. + + Workers-to-Main types + + - stdout, stderr: indicate stdout/stderr output from the wasm + layer. The data property is the string of the output, noting + that the emscripten binding emits these one line at a time. Thus, + if a C-side puts() emits multiple lines in a single call, the JS + side will see that as multiple calls. Example: + + {type:'stdout', data: 'Hi, world.'} + + - module: Status text. This is intended to alert the main thread + about module loading status so that, e.g., the main thread can + update a progress widget and DTRT when the module is finished + loading and available for work. Status messages come in the form + + {type:'module', data:{ + type:'status', + data: {text:string|null, step:1-based-integer} + } + + with an incrementing step value for each subsequent message. When + the module loading is complete, a message with a text value of + null is posted. + + - working: data='start'|'end'. Indicates that work is about to be + sent to the module or has just completed. This can be used, e.g., + to disable UI elements which should not be activated while work + is pending. Example: + + {type:'working', data:'start'} + + Main-to-Worker types: + + - shellExec: data=text to execute as if it had been entered in the + sqlite3 CLI shell app (as opposed to sqlite3_exec()). This event + causes the worker to emit a 'working' event (data='start') before + it starts and a 'working' event (data='end') when it finished. If + called while work is currently being executed it emits stderr + message instead of doing actual work, as the underlying db cannot + handle concurrent tasks. Example: + + {type:'shellExec', data: 'select * from sqlite_master'} + + - More TBD as the higher-level db layer develops. +*/ + +/* + Apparent browser(s) bug: console messages emitted may be duplicated + in the console, even though they're provably only run once. See: + + https://stackoverflow.com/questions/49659464 + + Noting that it happens in Firefox as well as Chrome. Harmless but + annoying. +*/ +"use strict"; +(function(){ + /** + Posts a message in the form {type,data}. If passed more than 2 + args, the 3rd must be an array of "transferable" values to pass + as the 2nd argument to postMessage(). */ + const wMsg = + (type,data,transferables)=>{ + postMessage({type, data}, transferables || []); + }; + const stdout = (...args)=>wMsg('stdout', args); + const stderr = (...args)=>wMsg('stderr', args); + const toss = (...args)=>{ + throw new Error(args.join(' ')); + }; + const fixmeOPFS = "(FIXME: won't work with OPFS-over-sqlite3_vfs.)"; + let sqlite3 /* gets assigned when the wasm module is loaded */; + + self.onerror = function(/*message, source, lineno, colno, error*/) { + const err = arguments[4]; + if(err && 'ExitStatus'==err.name){ + /* This is relevant for the sqlite3 shell binding but not the + lower-level binding. */ + fiddleModule.isDead = true; + stderr("FATAL ERROR:", err.message); + stderr("Restarting the app requires reloading the page."); + wMsg('error', err); + } + console.error(err); + fiddleModule.setStatus('Exception thrown, see JavaScript console: '+err); + }; + + const Sqlite3Shell = { + /** Returns the name of the currently-opened db. */ + dbFilename: function f(){ + if(!f._) f._ = sqlite3.wasm.xWrap('fiddle_db_filename', "string", ['string']); + return f._(0); + }, + dbHandle: function f(){ + if(!f._) f._ = sqlite3.wasm.xWrap("fiddle_db_handle", "sqlite3*"); + return f._(); + }, + dbIsOpfs: function f(){ + return sqlite3.opfs && sqlite3.capi.sqlite3_js_db_uses_vfs( + this.dbHandle(), "opfs" + ); + }, + runMain: function f(){ + if(f.argv) return 0===f.argv.rc; + const dbName = "/fiddle.sqlite3"; + f.argv = [ + 'sqlite3-fiddle.wasm', + '-bail', '-safe', + dbName + /* Reminder: because of how we run fiddle, we have to ensure + that any argv strings passed to its main() are valid until + the wasm environment shuts down. */ + ]; + const capi = sqlite3.capi, wasm = sqlite3.wasm; + /* We need to call sqlite3_shutdown() in order to avoid numerous + legitimate warnings from the shell about it being initialized + after sqlite3_initialize() has been called. This means, + however, that any initialization done by the JS code may need + to be re-done (e.g. re-registration of dynamically-loaded + VFSes). We need a more generic approach to running such + init-level code. */ + capi.sqlite3_shutdown(); + f.argv.pArgv = wasm.allocMainArgv(f.argv); + f.argv.rc = wasm.exports.fiddle_main( + f.argv.length, f.argv.pArgv + ); + if(f.argv.rc){ + stderr("Fatal error initializing sqlite3 shell."); + fiddleModule.isDead = true; + return false; + } + stdout("SQLite version", capi.sqlite3_libversion(), + capi.sqlite3_sourceid().substr(0,19)); + stdout('Welcome to the "fiddle" shell.'); + if(sqlite3.opfs){ + stdout("\nOPFS is available. To open a persistent db, use:\n\n", + " .open file:name?vfs=opfs\n\nbut note that some", + "features (e.g. upload) do not yet work with OPFS."); + sqlite3.opfs.registerVfs(); + } + stdout('\nEnter ".help" for usage hints.'); + this.exec([ // initialization commands... + '.nullvalue NULL', + '.headers on' + ].join('\n')); + return true; + }, + /** + Runs the given text through the shell as if it had been typed + in by a user. Fires a working/start event before it starts and + working/end event when it finishes. + */ + exec: function f(sql){ + if(!f._){ + if(!this.runMain()) return; + f._ = sqlite3.wasm.xWrap('fiddle_exec', null, ['string']); + } + if(fiddleModule.isDead){ + stderr("shell module has exit()ed. Cannot run SQL."); + return; + } + wMsg('working','start'); + try { + if(f._running){ + stderr('Cannot run multiple commands concurrently.'); + }else if(sql){ + if(Array.isArray(sql)) sql = sql.join(''); + f._running = true; + f._(sql); + } + }finally{ + delete f._running; + wMsg('working','end'); + } + }, + resetDb: function f(){ + if(!f._) f._ = sqlite3.wasm.xWrap('fiddle_reset_db', null); + stdout("Resetting database."); + f._(); + stdout("Reset",this.dbFilename()); + }, + /* Interrupt can't work: this Worker is tied up working, so won't get the + interrupt event which would be needed to perform the interrupt. */ + interrupt: function f(){ + if(!f._) f._ = sqlite3.wasm.xWrap('fiddle_interrupt', null); + stdout("Requesting interrupt."); + f._(); + } + }; + + self.onmessage = function f(ev){ + ev = ev.data; + if(!f.cache){ + f.cache = { + prevFilename: null + }; + } + //console.debug("worker: onmessage.data",ev); + switch(ev.type){ + case 'shellExec': Sqlite3Shell.exec(ev.data); return; + case 'db-reset': Sqlite3Shell.resetDb(); return; + case 'interrupt': Sqlite3Shell.interrupt(); return; + /** Triggers the export of the current db. Fires an + event in the form: + + {type:'db-export', + data:{ + filename: name of db, + buffer: contents of the db file (Uint8Array), + error: on error, a message string and no buffer property. + } + } + */ + case 'db-export': { + const fn = Sqlite3Shell.dbFilename(); + stdout("Exporting",fn+"."); + const fn2 = fn ? fn.split(/[/\\]/).pop() : null; + try{ + if(!fn2) toss("DB appears to be closed."); + const buffer = sqlite3.capi.sqlite3_js_db_export( + Sqlite3Shell.dbHandle() + ); + wMsg('db-export',{filename: fn2, buffer: buffer.buffer}, [buffer.buffer]); + }catch(e){ + console.error("Export failed:",e); + /* Post a failure message so that UI elements disabled + during the export can be re-enabled. */ + wMsg('db-export',{ + filename: fn, + error: e.message + }); + } + return; + } + case 'open': { + /* Expects: { + buffer: ArrayBuffer | Uint8Array, + filename: the filename for the db. Any dir part is + stripped. + } + */ + const opt = ev.data; + let buffer = opt.buffer; + stderr('open():',fixmeOPFS); + if(buffer instanceof ArrayBuffer){ + buffer = new Uint8Array(buffer); + }else if(!(buffer instanceof Uint8Array)){ + stderr("'open' expects {buffer:Uint8Array} containing an uploaded db."); + return; + } + const fn = ( + opt.filename + ? opt.filename.split(/[/\\]/).pop().replace('"','_') + : ("db-"+((Math.random() * 10000000) | 0)+ + "-"+((Math.random() * 10000000) | 0)+".sqlite3") + ); + try { + /* We cannot delete the existing db file until the new one + is installed, which means that we risk overflowing our + quota (if any) by having both the previous and current + db briefly installed in the virtual filesystem. */ + const fnAbs = '/'+fn; + const oldName = Sqlite3Shell.dbFilename(); + if(oldName && oldName===fnAbs){ + /* We cannot create the replacement file while the current file + is opened, nor does the shell have a .close command, so we + must temporarily switch to another db... */ + Sqlite3Shell.exec('.open :memory:'); + fiddleModule.FS.unlink(fnAbs); + } + fiddleModule.FS.createDataFile("/", fn, buffer, true, true); + Sqlite3Shell.exec('.open "'+fnAbs+'"'); + if(oldName && oldName!==fnAbs){ + try{fiddleModule.fsUnlink(oldName)} + catch(e){/*ignored*/} + } + stdout("Replaced DB with",fn+"."); + }catch(e){ + stderr("Error installing db",fn+":",e.message); + } + return; + } + }; + console.warn("Unknown fiddle-worker message type:",ev); + }; + + /** + emscripten module for use with build mode -sMODULARIZE. + */ + const fiddleModule = { + print: stdout, + printErr: stderr, + /** + Intercepts status updates from the emscripting module init + and fires worker events with a type of 'status' and a + payload of: + + { + text: string | null, // null at end of load process + step: integer // starts at 1, increments 1 per call + } + + We have no way of knowing in advance how many steps will + be processed/posted, so creating a "percentage done" view is + not really practical. One can be approximated by giving it a + current value of message.step and max value of message.step+1, + though. + + When work is finished, a message with a text value of null is + submitted. + + After a message with text==null is posted, the module may later + post messages about fatal problems, e.g. an exit() being + triggered, so it is recommended that UI elements for posting + status messages not be outright removed from the DOM when + text==null, and that they instead be hidden until/unless + text!=null. + */ + setStatus: function f(text){ + if(!f.last) f.last = { step: 0, text: '' }; + else if(text === f.last.text) return; + f.last.text = text; + wMsg('module',{ + type:'status', + data:{step: ++f.last.step, text: text||null} + }); + } + }; + + importScripts('fiddle-module.js'+self.location.search); + /** + initFiddleModule() is installed via fiddle-module.js due to + building with: + + emcc ... -sMODULARIZE=1 -sEXPORT_NAME=initFiddleModule + */ + sqlite3InitModule(fiddleModule).then((_sqlite3)=>{ + sqlite3 = _sqlite3; + const dbVfs = sqlite3.wasm.xWrap('fiddle_db_vfs', "*", ['string']); + fiddleModule.fsUnlink = (fn)=>{ + return sqlite3.wasm.sqlite3_wasm_vfs_unlink(dbVfs(0), fn); + }; + wMsg('fiddle-ready'); + })/*then()*/; +})(); |