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 "ts/libts.h"
29 #include "I_EventSystem.h"
30 #if !defined(I_VIO_h)
31 #error "include I_VIO.h"
32 -- -
33   include I_VIO.h
34 #endif
35 
36 //
37 // Data Types
38 //
39 #define VCONNECTION_CACHE_DATA_BASE 0
40 #define VCONNECTION_NET_DATA_BASE 100
41 #define VCONNECTION_API_DATA_BASE 200
42 
43 //
44 // Event signals
45 //
46 
47 #define VC_EVENT_NONE EVENT_NONE
48 
49 /** When a Continuation is first scheduled on a processor. */
50 #define VC_EVENT_IMMEDIATE EVENT_IMMEDIATE
51 
52 #define VC_EVENT_READ_READY VC_EVENT_EVENTS_START
53 
54 /**
55   Any data in the accociated buffer *will be written* when the
56   Continuation returns.
57 
58 */
59 #define VC_EVENT_WRITE_READY (VC_EVENT_EVENTS_START + 1)
60 
61 #define VC_EVENT_READ_COMPLETE (VC_EVENT_EVENTS_START + 2)
62 #define VC_EVENT_WRITE_COMPLETE (VC_EVENT_EVENTS_START + 3)
63 
64 /**
65   No more data (end of stream). It should be interpreted by a
66   protocol engine as either a COMPLETE or ERROR.
67 
68 */
69 #define VC_EVENT_EOS (VC_EVENT_EVENTS_START + 4)
70 
71 #define VC_EVENT_ERROR EVENT_ERROR
72 
73 /**
74   VC_EVENT_INACTIVITY_TIMEOUT indiates that the operation (read or write) has:
75     -# been enabled for more than the inactivity timeout period
76        (for a read, there has been space in the buffer)
77        (for a write, there has been data in the buffer)
78     -# no progress has been made
79        (for a read, no data has been read from the connection)
80        (for a write, no data has been written to the connection)
81 
82 */
83 #define VC_EVENT_INACTIVITY_TIMEOUT (VC_EVENT_EVENTS_START + 5)
84 
85 /**
86   Total time for some operation has been exeeded, regardless of any
87   intermediate progress.
88 
89 */
90 #define VC_EVENT_ACTIVE_TIMEOUT (VC_EVENT_EVENTS_START + 6)
91 
92 #define VC_EVENT_OOB_COMPLETE (VC_EVENT_EVENTS_START + 7)
93 
94 //
95 // Event names
96 //
97 
98 //
99 // VC_EVENT_READ_READ occurs when data *has been written* into
100 // the associated buffer.
101 //
102 // VC_EVENT_ERROR indicates that some error has occured.  The
103 // "data" will be either 0 if the errno is unavailable or errno.
104 //
105 // VC_EVENT_INTERVAL indidates that an interval timer has expired.
106 //
107 
108 //
109 // Event return codes
110 //
111 #define VC_EVENT_DONE CONTINUATION_DONE
112 #define VC_EVENT_CONT CONTINUATION_CONT
113 
114   //////////////////////////////////////////////////////////////////////////////
115   //
116   //      Support Data Structures
117   //
118   //////////////////////////////////////////////////////////////////////////////
119 
120   /** Used in VConnection::shutdown(). */
121   enum ShutdownHowTo_t {
122     IO_SHUTDOWN_READ = 0,
123     IO_SHUTDOWN_WRITE,
124     IO_SHUTDOWN_READWRITE
125   };
126 
127 /** Used in VConnection::get_data(). */
128 enum TSApiDataType {
129   TS_API_DATA_READ_VIO = VCONNECTION_API_DATA_BASE,
130   TS_API_DATA_WRITE_VIO,
131   TS_API_DATA_OUTPUT_VC,
132   TS_API_DATA_CLOSED,
133   TS_API_DATA_LAST ///< Used by other classes to extend the enum values.
134 };
135 
136 extern "C" {
137 typedef struct tsapi_vio *TSVIO;
138 }
139 
140 /**
141   Base class for the connection classes that provide IO capabilities.
142 
143   The VConnection class is an abstract representation of a uni or
144   bi-directional data conduit returned by a Processor. In a sense,
145   they serve a similar purpose to file descriptors. A VConnection
146   is a pure base class that defines methods to perform stream IO.
147   It is also a Continuation that is called back from processors.
148 
149 */
150 class VConnection : public Continuation
151 {
152 public:
153   virtual ~VConnection();
154 
155   /**
156     Read data from the VConnection.
157 
158     Called by a state machine to read data from the VConnection.
159     Processors implementing read functionality take out lock, put
160     new bytes on the buffer and call the continuation back before
161     releasing the lock in order to enable the state machine to
162     handle transfer schemes where the end of a given transaction
163     is marked by a special character (ie: NNTP).
164 
165     <b>Possible Event Codes</b>
166 
167     On the callback to the continuation, the VConnection may use
168     on of the following values for the event code:
169 
170     <table border="1">
171       <tr>
172         <td align="center"><b>Event code</b></td>
173         <td align="center"><b>Meaning</b></td>
174       </tr>
175       <tr>
176         <td>VC_EVENT_READ_READY</td>
177         <td>Data has been added to the buffer or the buffer is full</td>
178       </tr>
179       <tr>
180         <td>VC_EVENT_READ_COMPLETE</td>
181         <td>The amount of data indicated by 'nbytes' has been read into the
182             buffer</td>
183       </tr>
184       <tr>
185         <td>VC_EVENT_EOS</td>
186         <td>The stream being read from has been shutdown</td>
187       </tr>
188       <tr>
189         <td>VC_EVENT_ERROR</td>
190         <td>An error occurred during the read</td>
191       </tr>
192     </table>
193 
194     @param c Continuation to be called back with events.
195     @param nbytes Number of bytes to read. If unknown, nbytes must
196       be set to INT64_MAX.
197     @param buf buffer to read into.
198     @return VIO representing the scheduled IO operation.
199 
200   */
201   virtual VIO *do_io_read(Continuation *c = NULL, int64_t nbytes = INT64_MAX, MIOBuffer *buf = 0) = 0;
202 
203   /**
204     Write data to the VConnection.
205 
206     This method is called by a state machine to write data to the
207     VConnection.
208 
209     <b>Possible Event Codes</b>
210 
211     On the callback to the continuation, the VConnection may use
212     on of the following event codes:
213 
214     <table border="1">
215       <tr>
216         <td align="center"><b>Event code</b></td>
217         <td align="center"><b>Meaning</b></td>
218       </tr>
219       <tr>
220         <td>VC_EVENT_WRITE_READY</td>
221         <td>Data was written from the reader or there are no bytes available
222         for the reader to write.</td>
223       </tr>
224       <tr>
225         <td>VC_EVENT_WRITE_COMPLETE</td>
226         <td>The amount of data indicated by 'nbytes' has been written to the
227             VConnection</td>
228       </tr>
229       <tr>
230         <td>VC_EVENT_INACTIVITY_TIMEOUT</td>
231         <td>No activity was performed for a certain period.</td>
232       </tr>
233       <tr>
234         <td>VC_EVENT_ACTIVE_TIMEOUT</td>
235         <td>Write operation continued beyond a time limit.</td>
236       </tr>
237       <tr>
238         <td>VC_EVENT_ERROR</td>
239         <td>An error occurred during the write</td>
240       </tr>
241     </table>
242 
243     @param c Continuation to be called back with events.
244     @param nbytes Number of bytes to write. If unknown, nbytes must
245       be set to INT64_MAX.
246     @param buf Reader whose data is to be read from.
247     @param owner
248     @return VIO representing the scheduled IO operation.
249 
250   */
251   virtual VIO *do_io_write(Continuation *c = NULL, int64_t nbytes = INT64_MAX, IOBufferReader *buf = 0, bool owner = false) = 0;
252 
253   /**
254     Indicate that the VConnection is no longer needed.
255 
256     Once the state machine has finished using this VConnection, it
257     must call this function to indicate that the VConnection can
258     be deallocated.  After a close has been called, the VConnection
259     and underlying processor must not send any more events related
260     to this VConnection to the state machine. Likeswise, the state
261     machine must not access the VConnection or any VIOs obtained
262     from it after calling this method.
263 
264     @param lerrno indicates where a close is a normal close or an
265       abort. The difference between a normal close and an abort
266       depends on the underlying type of the VConnection.
267 
268   */
269   virtual void do_io_close(int lerrno = -1) = 0;
270 
271   /**
272     Terminate one or both directions of the VConnection.
273 
274     Indicates that one or both sides of the VConnection should be
275     terminated. After this call is issued, no further I/O can be
276     done on the specified direction of the connection. The processor
277     must not send any further events (including timeout events) to
278     the state machine, and the state machine must not use any VIOs
279     from a shutdown direction of the connection. Even if both sides
280     of a connection are shutdown, the state machine must still call
281     do_io_close() when it wishes the VConnection to be deallocated.
282 
283     <b>Possible howto values</b>
284 
285     <table border="1">
286       <tr>
287         <td align="center"><b>Value</b></td>
288         <td align="center"><b>Meaning</b></td>
289       </tr>
290       <tr>
291         <td>IO_SHUTDOWN_READ</td>
292         <td>Indicates that this VConnection should not generate any more
293         read events</td>
294       </tr>
295       <tr>
296         <td>IO_SHUTDOWN_WRITE</td>
297         <td>Indicates that this VConnection should not generate any more
298         write events</td>
299       </tr>
300       <tr>
301         <td>IO_SHUTDOWN_READWRITE</td>
302         <td>Indicates that this VConnection should not generate any more
303         read nor write events</td>
304       </tr>
305     </table>
306 
307     @param howto Specifies which direction of the VConnection to
308       shutdown.
309 
310   */
311   virtual void do_io_shutdown(ShutdownHowTo_t howto) = 0;
312 
313   VConnection(ProxyMutex *aMutex);
314 
315   /** @deprecated */
316   VIO *do_io(int op, Continuation *c = NULL, int64_t nbytes = INT64_MAX, MIOBuffer *buf = 0, int data = 0);
317 
318   // Private
319   // Set continuation on a given vio. The public interface
320   // is through VIO::set_continuation()
321   virtual void set_continuation(VIO *vio, Continuation *cont);
322 
323   // Reenable a given vio.  The public interface is through VIO::reenable
324   virtual void reenable(VIO *vio);
325   virtual void reenable_re(VIO *vio);
326 
327   /**
328     Convenience function to retrieve information from VConnection.
329 
330     This function is provided as a convenience for state machines
331     to transmit information from/to a VConnection without breaking
332     the VConnection abstraction. Its behavior varies depending on
333     the type of VConnection being used.
334 
335     @param id Identifier associated to interpret the data field
336     @param data Value or pointer with state machine or VConnection data.
337     @return True if the oparation is successful.
338 
339   */
340   virtual bool
341   get_data(int id, void *data)
342   {
343     (void)id;
344     (void)data;
345     return false;
346   }
347 
348   /**
349     Convenience function to set information into the VConnection.
350 
351     This function is provided as a convenience for state machines
352     to transmit information from/to a VConnection without breaking
353     the VConnection abstraction. Its behavior varies depending on
354     the type of VConnection being used.
355 
356     @param id Identifier associated to interpret the data field.
357     @param data Value or pointer with state machine or VConnection data.
358     @return True if the oparation is successful.
359 
360   */
361   virtual bool
362   set_data(int id, void *data)
363   {
364     (void)id;
365     (void)data;
366     return false;
367   }
368 
369 public:
370   /**
371     The error code from the last error.
372 
373     Indicates the last error on the VConnection. They are either
374     system error codes or from the InkErrno.h file.
375 
376   */
377   int lerrno;
378 };
379 
380 struct DummyVConnection : public VConnection {
381   virtual VIO *
382   do_io_write(Continuation * /* c ATS_UNUSED */, int64_t /* nbytes ATS_UNUSED */, IOBufferReader * /* buf ATS_UNUSED */,
383               bool /* owner ATS_UNUSED */)
384   {
385     ink_assert(!"VConnection::do_io_write -- "
386                 "cannot use default implementation");
387     return NULL;
388   }
389   virtual VIO *
390   do_io_read(Continuation * /* c ATS_UNUSED */, int64_t /* nbytes ATS_UNUSED */, MIOBuffer * /* buf ATS_UNUSED */)
391   {
392     ink_assert(!"VConnection::do_io_read -- "
393                 "cannot use default implementation");
394     return NULL;
395   }
396   virtual void
397   do_io_close(int /* alerrno ATS_UNUSED */)
398   {
399     ink_assert(!"VConnection::do_io_close -- "
400                 "cannot use default implementation");
401   }
402   virtual void do_io_shutdown(ShutdownHowTo_t /* howto ATS_UNUSED */)
403   {
404     ink_assert(!"VConnection::do_io_shutdown -- "
405                 "cannot use default implementation");
406   }
407   DummyVConnection(ProxyMutex *m) : VConnection(m) {}
408 };
409 
410 #endif /*_I_VConnection_h_*/
411