return retval;
}
+/* To facilitate the implementation of the pkgInternetAgent class, which
+ * is declared below:
+ */
+#if IMPLEMENTATION_LEVEL == SETUP_TOOL_COMPONENT
+
+/* Within the setup tool, the pkgInternetAgent::SetRetryOptions() method
+ * requires a pointer to a pkgSetupAction...
+ */
+ typedef pkgSetupAction *INTERNET_RETRY_REQUESTER;
+
+#else
+/* ...whereas, in the general case, it requires a pointer to a pkgXmlNode.
+ */
+ typedef pkgXmlNode *INTERNET_RETRY_REQUESTER;
+
+#endif
+
class pkgInternetAgent
{
/* A minimal, locally implemented class, instantiated ONCE as a
*/
private:
HINTERNET SessionHandle;
+ int connection_delay, delay_factor, retries, retry_interval;
public:
inline pkgInternetAgent():SessionHandle( NULL )
if( SessionHandle != NULL )
Close( SessionHandle );
}
+ void SetRetryOptions( INTERNET_RETRY_REQUESTER, const char* );
HINTERNET OpenURL( const char* );
/* Remaining methods are simple inline wrappers for the
free( (void *)(dest_file) );
}
+void pkgInternetAgent::SetRetryOptions
+( INTERNET_RETRY_REQUESTER referrer, const char *url_template )
+{
+ /* Initialisation method, invoked immediately prior to the start
+ * of each archive download request, to establish the options for
+ * retrying any failed host connection request.
+ *
+ * The first of any sequence of connection attempts may always be
+ * initiated immediately.
+ */
+ connection_delay = 0;
+
+ /* If any further attempts are necessary, we will delay them
+ * at progressively increasing intervals, to give us the best
+ * possible chance to circumvent throttling of excess frequency
+ * connection requests, by the download server.
+ *
+ * FIXME: for each change of host domain, we should establish
+ * settings by consulting the configuration profile; for the
+ * time being, we simply assign fixed defaults.
+ */
+ delay_factor = INTERNET_DELAY_FACTOR;
+ retry_interval = INTERNET_RETRY_INTERVAL;
+ retries = INTERNET_RETRY_ATTEMPTS;
+}
+
HINTERNET pkgInternetAgent::OpenURL( const char *URL )
{
/* Open an internet data stream.
/* Aggressively attempt to acquire a resource handle, which we may use
* to access the specified URL; (schedule a maximum of five attempts).
*/
- int retries = 5;
do { pkgDownloadMeter::SpinWait( 1, URL );
+
+ /* Distribute retries at geometrically incrementing intervals.
+ */
+ if( connection_delay > 0 )
+ /* This is not the first time we've tried to open this URL;
+ * compute the appropriate retry interval, and wait between
+ * successive attempts to establish the connection.
+ */
+ Sleep( connection_delay = delay_factor * connection_delay );
+ else
+ /* This is the first attempt to open this URL; don't wait,
+ * but set up the baseline, in milliseconds, for interval
+ * computation, in the event that further attempts may be
+ * required.
+ */
+ connection_delay = retry_interval;
+
ResourceHandle = InternetOpenUrl
(
/* Here, we attempt to assign a URL specific resource handle,
* unless we have exhausted the specified retry limit...
*/
if( --retries < 1 )
- /*
- * ...in which case, we diagnose failure to open the URL.
+ {
+ /* ...in which case, we diagnose failure to open the URL.
*/
+ DEBUG_INVOKE_IF( DEBUG_REQUEST( DEBUG_TRACE_INTERNET_REQUESTS ),
+ dmh_printf( "%s\nConnection failed(status=%u); abandoned.\n",
+ URL, GetLastError() )
+ );
dmh_notify( DMH_ERROR, "%s:cannot open URL\n", URL );
-
+ }
else DEBUG_INVOKE_IF( DEBUG_REQUEST( DEBUG_TRACE_INTERNET_REQUESTS ),
- dmh_printf( "%s\nConnecting ... failed(status=%u); retrying...\n",
- URL, GetLastError() )
+ dmh_printf( "%s\nConnecting ... failed(status=%u); retrying in %ds...\n",
+ URL, GetLastError(), delay_factor * connection_delay / 1000 )
);
}
else
if( url_template != NULL )
{
/* ...from the URL constructed from the template specified in
- * the package repository catalogue (configuration database)...
+ * the package repository catalogue (configuration database).
*/
const char *mirror = get_host_info( Selection(), mirror_key );
char package_url[mkpath( NULL, url_template, package_name, mirror )];
mkpath( package_url, url_template, package_name, mirror );
+
+ /* Enable retrying of failed connection attempts, according to the
+ * preferences, if any, which have been configured for the repository
+ * associated with the current URL template, or with default settings
+ * otherwise, then initiate the package download process.
+ */
+ pkgDownloadAgent.SetRetryOptions( Selection(), url_template );
if( download.Get( package_url ) > 0 )
/*
* Download was successful; clear the pending and failure flags.
const char *mirror = repository->GetPropVal( mirror_key, NULL );
char catalogue_url[mkpath( NULL, url_template, name, mirror )];
mkpath( catalogue_url, url_template, name, mirror );
-//dmh_printf( "SyncRepository: get %s ...\n", catalogue_url );
+
+ /* Enable retries according to the preferences, if any, as
+ * configured for the repository, or adopt default settings
+ * otherwise, then initiate the download process for the
+ * catalogue file.
+ */
+ pkgDownloadAgent.SetRetryOptions( repository, url_template );
if( download.Get( catalogue_url ) <= 0 )
dmh_notify( DMH_ERROR,
"Sync Repository: %s: download failed\n", catalogue_url
);
-//dmh_printf( "SyncRepository: get %s completed\n", catalogue_url );
}
/* We will only replace our current working copy of this catalogue,
*/
#define PKGINET_H 1
+/* profile.xml may specify the maximum number of retries which will
+ * be permitted, for each configured repository, when any attempt to
+ * establish a download connection fails. In the event that this is
+ * not specified in profile.xml, the following default will apply:
+ */
+#define INTERNET_RETRY_ATTEMPTS 5
+
+/* In the default case, when profile.xml doesn't stipulate options,
+ * specify the interval, in milliseconds, to wait between successive
+ * retries to open any one URL. The first attempt for each individual
+ * URL is immediate; if it fails, the first retry is scheduled after
+ *
+ * INTERNET_RETRY_INTERVAL * INTERNET_DELAY_FACTOR milliseconds
+ *
+ * In the event that further retries are necessary, they are scheduled
+ * at geometrically incrementing intervals, by multiplying the interval
+ * from the preceding attempt by INTERNET_DELAY_FACTOR, prior to each
+ * successive connection attempt.
+ */
+#define INTERNET_DELAY_FACTOR 2
+#define INTERNET_RETRY_INTERVAL 1000
+
class pkgDownloadMeter
{
/* Abstract base class, from which facilities for monitoring the
OSDN Git Service
