Annotation of fam/fam/ServerHost.h, Revision 1.1
1.1 ! trev 1: // Copyright (C) 1999 Silicon Graphics, Inc. All Rights Reserved.
! 2: //
! 3: // This program is free software; you can redistribute it and/or modify it
! 4: // under the terms of version 2 of the GNU General Public License as
! 5: // published by the Free Software Foundation.
! 6: //
! 7: // This program is distributed in the hope that it would be useful, but
! 8: // WITHOUT ANY WARRANTY; without even the implied warranty of
! 9: // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Further, any
! 10: // license provided herein, whether implied or otherwise, is limited to
! 11: // this program in accordance with the express provisions of the GNU
! 12: // General Public License. Patent licenses, if any, provided herein do not
! 13: // apply to combinations of this program with other product or programs, or
! 14: // any other product whatsoever. This program is distributed without any
! 15: // warranty that the program is delivered free of the rightful claim of any
! 16: // third person by way of infringement or the like. See the GNU General
! 17: // Public License for more details.
! 18: //
! 19: // You should have received a copy of the GNU General Public License along
! 20: // with this program; if not, write the Free Software Foundation, Inc., 59
! 21: // Temple Place - Suite 330, Boston MA 02111-1307, USA.
! 22:
! 23: #ifndef ServerHost_included
! 24: #define ServerHost_included
! 25:
! 26: #include <limits.h>
! 27: #include "Boolean.h"
! 28: #include "ClientInterest.h"
! 29: #include "RequestMap.h"
! 30: #include "RPC_TCP_Connector.h"
! 31: struct hostent;
! 32: class ServerConnection;
! 33:
! 34: // ServerHost represents an NFS-server host. A ServerHost tries to
! 35: // talk to remote fam. If it succeeds, it relies on remote fam to
! 36: // monitor files that reside on that host. If it can't talk to fam,
! 37: // it polls the files of interest.
! 38: //
! 39: // send_monitor() et al are used to tell the ServerHost what files
! 40: // are being monitored. If we have a connection to a remote fam,
! 41: // we send the appropriate message.
! 42: //
! 43: // When a file is monitored, a request number is allocated for it,
! 44: // and it is added to a RequestMap. When it's cancelled, it's
! 45: // removed from the RequestMap.
! 46: //
! 47: // A ServerHost is "active" if we're monitoring at least one file on
! 48: // that host. The ServerHost starts trying to connect to remote fam
! 49: // when it becomes active. When it becomes inactive, it starts a
! 50: // timer; if it stays inactive for three seconds, it disconnects from
! 51: // remote fam.
! 52: //
! 53: // So a ServerHost can be "active" but not "connected": there is no
! 54: // remote fam or its connection hasn't come up yet. A ServerHost can
! 55: // also be "connected" but not "active": its connection is timing
! 56: // out.
! 57: //
! 58: // Unfortunately, the kernel's NFS attribute cache gets in fam's way.
! 59: // If we scan a file within n seconds of someone else scanning the
! 60: // same file (n defaults to 3), then we get stale information from
! 61: // the cache. So we scan the file immediately, just in case the
! 62: // cache won't bite us, then we put the file into a queue of files to
! 63: // rescan n seconds later, the deferred scan queue.
! 64:
! 65: class ServerHost {
! 66:
! 67: public:
! 68:
! 69: bool is_connected() const { return connection != 0; }
! 70: const char *name() const { return myname; }
! 71:
! 72: Request send_monitor(ClientInterest *, ClientInterest::Type,
! 73: const char *remote_path);
! 74: void send_cancel(Request);
! 75: void send_suspend(Request);
! 76: void send_resume(Request);
! 77:
! 78: void poll();
! 79:
! 80: private:
! 81:
! 82: // A DeferredScan is the info needed to rescan an Interest after
! 83: // several seconds' delay. The delay is needed to let the NFS
! 84: // attribute cache go stale.
! 85:
! 86: class DeferredScan {
! 87:
! 88: public:
! 89:
! 90: inline DeferredScan(int then, int retries, Request = 0, const char * = 0);
! 91:
! 92: operator int () { return myrequest != 0; }
! 93:
! 94: Request request() const { return myrequest; }
! 95: const char *path() const { return mypath[0] ? mypath : NULL; }
! 96:
! 97: int when; // absolute time, in seconds
! 98: int retries; // how many times to try
! 99: class DeferredScan *next;
! 100:
! 101: private:
! 102:
! 103: Request myrequest;
! 104: char mypath[NAME_MAX];
! 105:
! 106: };
! 107:
! 108: // Instance Variables
! 109:
! 110: enum {RETRY_INTERVAL = 10};
! 111:
! 112: unsigned refcount;
! 113: char *myname;
! 114: RPC_TCP_Connector connector;
! 115: ServerConnection *connection;
! 116: Request unique_request;
! 117: RequestMap requests;
! 118: DeferredScan *deferred_scans;
! 119: DeferredScan *last;
! 120: int min_time;
! 121:
! 122: // Private Instance Methods
! 123:
! 124: ServerHost(const hostent&);
! 125: ~ServerHost();
! 126: bool active() { return requests.size() != 0; }
! 127: void activate();
! 128: void deactivate();
! 129: void defer_scan(int when, int retries, Request r , const char * path);
! 130:
! 131: // Class Methods
! 132:
! 133: static void connect_handler(int fd, void *);
! 134: static void disconnect_handler(void *);
! 135:
! 136: static void event_handler(const Event*, Request, const char *, void *);
! 137: static void deferred_scan_task(void *);
! 138: static void timeout_task(void *);
! 139:
! 140: ServerHost(const ServerHost&); // Do not copy
! 141: ServerHost & operator = (const ServerHost&); // or assign.
! 142:
! 143: friend class ServerHostRef;
! 144:
! 145: };
! 146:
! 147: #endif /* !ServerHost_included */
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