1 /** @file
2 
3   Public VConnection declaration and associated declarations
4 
5   @section license License
6 
7   Licensed to the Apache Software Foundation (ASF) under one
8   or more contributor license agreements.  See the NOTICE file
9   distributed with this work for additional information
10   regarding copyright ownership.  The ASF licenses this file
11   to you under the Apache License, Version 2.0 (the
12   "License"); you may not use this file except in compliance
13   with the License.  You may obtain a copy of the License at
14 
15       http://www.apache.org/licenses/LICENSE-2.0
16 
17   Unless required by applicable law or agreed to in writing, software
18   distributed under the License is distributed on an "AS IS" BASIS,
19   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
20   See the License for the specific language governing permissions and
21   limitations under the License.
22 
23  */
24 
25 #if !defined (_I_VConnection_h_)
26 #define _I_VConnection_h_
27 
28 #include "libts.h"
29 #include "I_EventSystem.h"
30 #if !defined(I_VIO_h)
31 #error "include I_VIO.h"
32 -- -include I_VIO.h
33 #endif
34 
35 //
36 // Data Types
37 //
38 #define VCONNECTION_CACHE_DATA_BASE     0
39 #define VCONNECTION_NET_DATA_BASE       100
40 #define VCONNECTION_API_DATA_BASE       200
41 
42 //
43 // Event signals
44 //
45 
46 #define VC_EVENT_NONE                    EVENT_NONE
47 
48 /** When a Continuation is first scheduled on a processor. */
49 #define VC_EVENT_IMMEDIATE               EVENT_IMMEDIATE
50 
51 #define	VC_EVENT_READ_READY              VC_EVENT_EVENTS_START
52 
53 /**
54   Any data in the accociated buffer *will be written* when the
55   Continuation returns.
56 
57 */
58 #define	VC_EVENT_WRITE_READY             (VC_EVENT_EVENTS_START+1)
59 
60 #define	VC_EVENT_READ_COMPLETE           (VC_EVENT_EVENTS_START+2)
61 #define	VC_EVENT_WRITE_COMPLETE          (VC_EVENT_EVENTS_START+3)
62 
63 /**
64   No more data (end of stream). It should be interpreted by a
65   protocol engine as either a COMPLETE or ERROR.
66 
67 */
68 #define	VC_EVENT_EOS                     (VC_EVENT_EVENTS_START+4)
69 
70 #define	VC_EVENT_ERROR                   EVENT_ERROR
71 
72 /**
73   VC_EVENT_INACTIVITY_TIMEOUT indiates that the operation (read or write) has:
74     -# been enabled for more than the inactivity timeout period
75        (for a read, there has been space in the buffer)
76        (for a write, there has been data in the buffer)
77     -# no progress has been made
78        (for a read, no data has been read from the connection)
79        (for a write, no data has been written to the connection)
80 
81 */
82 #define	VC_EVENT_INACTIVITY_TIMEOUT      (VC_EVENT_EVENTS_START+5)
83 
84 /**
85   Total time for some operation has been exeeded, regardless of any
86   intermediate progress.
87 
88 */
89 #define	VC_EVENT_ACTIVE_TIMEOUT          (VC_EVENT_EVENTS_START+6)
90 
91 #define	VC_EVENT_OOB_COMPLETE            (VC_EVENT_EVENTS_START+7)
92 
93 //
94 // Event names
95 //
96 
97 //
98 // VC_EVENT_READ_READ occurs when data *has been written* into
99 // the associated buffer.
100 //
101 // VC_EVENT_ERROR indicates that some error has occured.  The
102 // "data" will be either 0 if the errno is unavailable or errno.
103 //
104 // VC_EVENT_INTERVAL indidates that an interval timer has expired.
105 //
106 
107 //
108 // Event return codes
109 //
110 #define VC_EVENT_DONE                CONTINUATION_DONE
111 #define VC_EVENT_CONT                CONTINUATION_CONT
112 
113 //////////////////////////////////////////////////////////////////////////////
114 //
115 //      Support Data Structures
116 //
117 //////////////////////////////////////////////////////////////////////////////
118   class VConnection;
119 
120 typedef int (VConnection::*VConnectionHandler) (int event, void *data);
121 
122 /** Used in VConnection::shutdown(). */
123 enum ShutdownHowTo_t
124 {
125   IO_SHUTDOWN_READ = 0,
126   IO_SHUTDOWN_WRITE,
127   IO_SHUTDOWN_READWRITE
128 };
129 
130 /** Used in VConnection::get_data(). */
131 enum TSApiDataType
132 {
133   TS_API_DATA_READ_VIO = VCONNECTION_API_DATA_BASE,
134   TS_API_DATA_WRITE_VIO,
135   TS_API_DATA_OUTPUT_VC,
136   TS_API_DATA_CLOSED
137 };
138 
139 extern "C" {
140     typedef struct tsapi_vio* TSVIO;
141 }
142 
143 /**
144   Base class for the connection classes that provide IO capabilities.
145 
146   The VConnection class is an abstract representation of a uni or
147   bi-directional data conduit returned by a Processor. In a sense,
148   they serve a similar purpose to file descriptors. A VConnection
149   is a pure base class that defines methods to perform stream IO.
150   It is also a Continuation that is called back from processors.
151 
152 */
153 class VConnection:public Continuation
154 {
155 public:
156 
157   virtual ~ VConnection();
158 
159   /**
160     Read data from the VConnection.
161 
162     Called by a state machine to read data from the VConnection.
163     Processors implementing read functionality take out lock, put
164     new bytes on the buffer and call the continuation back before
165     releasing the lock in order to enable the state machine to
166     handle transfer schemes where the end of a given transaction
167     is marked by a special character (ie: NNTP).
168 
169     <b>Possible Event Codes</b>
170 
171     On the callback to the continuation, the VConnection may use
172     on of the following values for the event code:
173 
174     <table border="1">
175       <tr>
176         <td align="center"><b>Event code</b></td>
177         <td align="center"><b>Meaning</b></td>
178       </tr>
179       <tr>
180         <td>VC_EVENT_READ_READY</td>
181         <td>Data has been added to the buffer or the buffer is full</td>
182       </tr>
183       <tr>
184         <td>VC_EVENT_READ_COMPLETE</td>
185         <td>The amount of data indicated by 'nbytes' has been read into the
186             buffer</td>
187       </tr>
188       <tr>
189         <td>VC_EVENT_EOS</td>
190         <td>The stream being read from has been shutdown</td>
191       </tr>
192       <tr>
193         <td>VC_EVENT_ERROR</td>
194         <td>An error occurred during the read</td>
195       </tr>
196     </table>
197 
198     @param c Continuation to be called back with events.
199     @param nbytes Number of bytes to read. If unknown, nbytes must
200       be set to INT64_MAX.
201     @param buf buffer to read into.
202     @return VIO representing the scheduled IO operation.
203 
204   */
205   virtual VIO *do_io_read(Continuation *c = NULL, int64_t nbytes = INT64_MAX, MIOBuffer *buf = 0) = 0;
206 
207   /**
208     Write data to the VConnection.
209 
210     This method is called by a state machine to write data to the
211     VConnection.
212 
213     <b>Possible Event Codes</b>
214 
215     On the callback to the continuation, the VConnection may use
216     on of the following event codes:
217 
218     <table border="1">
219       <tr>
220         <td align="center"><b>Event code</b></td>
221         <td align="center"><b>Meaning</b></td>
222       </tr>
223       <tr>
224         <td>VC_EVENT_WRITE_READY</td>
225         <td>Data was written from the reader or there are no bytes available
226         for the reader to write.</td>
227       </tr>
228       <tr>
229         <td>VC_EVENT_WRITE_COMPLETE</td>
230         <td>The amount of data indicated by 'nbytes' has been written to the
231             VConnection</td>
232       </tr>
233       <tr>
234         <td>VC_EVENT_INACTIVITY_TIMEOUT</td>
235         <td>No activity was performed for a certain period.</td>
236       </tr>
237       <tr>
238         <td>VC_EVENT_ACTIVE_TIMEOUT</td>
239         <td>Write operation continued beyond a time limit.</td>
240       </tr>
241       <tr>
242         <td>VC_EVENT_ERROR</td>
243         <td>An error occurred during the write</td>
244       </tr>
245     </table>
246 
247     @param c Continuation to be called back with events.
248     @param nbytes Number of bytes to write. If unknown, nbytes must
249       be set to INT64_MAX.
250     @param buf Reader whose data is to be read from.
251     @param owner
252     @return VIO representing the scheduled IO operation.
253 
254   */
255   virtual VIO *do_io_write(Continuation *c = NULL,
256                            int64_t nbytes = INT64_MAX, IOBufferReader *buf = 0, bool owner = false) = 0;
257 
258   /**
259     Indicate that the VConnection is no longer needed.
260 
261     Once the state machine has finished using this VConnection, it
262     must call this function to indicate that the VConnection can
263     be deallocated.  After a close has been called, the VConnection
264     and underlying processor must not send any more events related
265     to this VConnection to the state machine. Likeswise, the state
266     machine must not access the VConnection or any VIOs obtained
267     from it after calling this method.
268 
269     @param lerrno indicates where a close is a normal close or an
270       abort. The difference between a normal close and an abort
271       depends on the underlying type of the VConnection.
272 
273   */
274   virtual void do_io_close(int lerrno = -1) = 0;
275 
276   /**
277     Terminate one or both directions of the VConnection.
278 
279     Indicates that one or both sides of the VConnection should be
280     terminated. After this call is issued, no further I/O can be
281     done on the specified direction of the connection. The processor
282     must not send any further events (including timeout events) to
283     the state machine, and the state machine must not use any VIOs
284     from a shutdown direction of the connection. Even if both sides
285     of a connection are shutdown, the state machine must still call
286     do_io_close() when it wishes the VConnection to be deallocated.
287 
288     <b>Possible howto values</b>
289 
290     <table border="1">
291       <tr>
292         <td align="center"><b>Value</b></td>
293         <td align="center"><b>Meaning</b></td>
294       </tr>
295       <tr>
296         <td>IO_SHUTDOWN_READ</td>
297         <td>Indicates that this VConnection should not generate any more
298         read events</td>
299       </tr>
300       <tr>
301         <td>IO_SHUTDOWN_WRITE</td>
302         <td>Indicates that this VConnection should not generate any more
303         write events</td>
304       </tr>
305       <tr>
306         <td>IO_SHUTDOWN_READWRITE</td>
307         <td>Indicates that this VConnection should not generate any more
308         read nor write events</td>
309       </tr>
310     </table>
311 
312     @param howto Specifies which direction of the VConnection to
313       shutdown.
314 
315   */
316   virtual void do_io_shutdown(ShutdownHowTo_t howto) = 0;
317 
318     VConnection(ProxyMutex *aMutex);
319 
320   /** @deprecated */
321   VIO *do_io(int op, Continuation *c = NULL, int64_t nbytes = INT64_MAX, MIOBuffer *buf = 0, int data = 0);
322 
323   // Private
324   // Set continuation on a given vio. The public interface
325   // is through VIO::set_continuation()
326   virtual void set_continuation(VIO *vio, Continuation *cont);
327 
328   // Reenable a given vio.  The public interface is through VIO::reenable
329   virtual void reenable(VIO *vio);
330   virtual void reenable_re(VIO *vio);
331 
332   /**
333     Convenience function to retrieve information from VConnection.
334 
335     This function is provided as a convenience for state machines
336     to transmit information from/to a VConnection without breaking
337     the VConnection abstraction. Its behavior varies depending on
338     the type of VConnection being used.
339 
340     @param id Identifier associated to interpret the data field
341     @param data Value or pointer with state machine or VConnection data.
342     @return True if the oparation is successful.
343 
344   */
345   virtual bool get_data(int id, void *data)
346   {
347     (void) id;
348     (void) data;
349     return false;
350   }
351 
352   /**
353     Convenience function to set information into the VConnection.
354 
355     This function is provided as a convenience for state machines
356     to transmit information from/to a VConnection without breaking
357     the VConnection abstraction. Its behavior varies depending on
358     the type of VConnection being used.
359 
360     @param id Identifier associated to interpret the data field.
361     @param data Value or pointer with state machine or VConnection data.
362     @return True if the oparation is successful.
363 
364   */
365   virtual bool set_data(int id, void *data)
366   {
367     (void) id;
368     (void) data;
369     return false;
370   }
371 
372 public:
373 
374   /**
375     The error code from the last error.
376 
377     Indicates the last error on the VConnection. They are either
378     system error codes or from the InkErrno.h file.
379 
380   */
381   int lerrno;
382 };
383 
384 struct DummyVConnection: public VConnection
385 {
386   virtual VIO *do_io_write(Continuation * /* c ATS_UNUSED */, int64_t /* nbytes ATS_UNUSED */, IOBufferReader * /* buf ATS_UNUSED */, bool /* owner ATS_UNUSED */) {
387     ink_assert(!"VConnection::do_io_write -- " "cannot use default implementation");
388     return NULL;
389   }
390   virtual VIO *do_io_read(Continuation * /* c ATS_UNUSED */, int64_t /* nbytes ATS_UNUSED */, MIOBuffer * /* buf ATS_UNUSED */) {
391     ink_assert(!"VConnection::do_io_read -- " "cannot use default implementation");
392     return NULL;
393   }
394   virtual void do_io_close(int /* alerrno ATS_UNUSED */) {
395     ink_assert(!"VConnection::do_io_close -- " "cannot use default implementation");
396   }
397   virtual void do_io_shutdown(ShutdownHowTo_t /* howto ATS_UNUSED */ )
398   {
399     ink_assert(!"VConnection::do_io_shutdown -- " "cannot use default implementation");
400   }
401 DummyVConnection(ProxyMutex *m):VConnection(m) {
402   }
403 };
404 
405 #endif /*_I_VConnection_h_*/
406