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Commit7195fb3

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initdb: Select working dynamic shared memory implementation.
If POSIX shared memory is supported and works, we prefer it.Otherwise, we prefer System V, except on Windows, where we usethe implementation specific to that platform.
1 parent15e46fd commit7195fb3

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‎src/bin/initdb/initdb.c

Lines changed: 60 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -56,6 +56,10 @@
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#include<signal.h>
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#include<time.h>
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#ifdefHAVE_SHM_OPEN
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#include"sys/mman.h"
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#endif
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#include"mb/pg_wchar.h"
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#include"getaddrinfo.h"
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#include"getopt_long.h"
@@ -150,6 +154,7 @@ static char *pgdata_native;
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/* defaults */
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staticintn_connections=10;
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staticintn_buffers=50;
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staticchar*dynamic_shared_memory_type=NULL;
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/*
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* Warning messages for authentication methods
@@ -1076,6 +1081,50 @@ set_null_conf(void)
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free(path);
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}
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/*
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* Determine which dynamic shared memory implementation should be used on
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* this platform. POSIX shared memory is preferable because the default
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* allocation limits are much higher than the limits for System V on most
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* systems that support both, but the fact that a platform has shm_open
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* doesn't guarantee that that call will succeed when attempted. So, we
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* attempt to reproduce what the postmaster will do when allocating a POSIX
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* segment in dsm_impl.c; if it doesn't work, we assume it won't work for
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* the postmaster either, and configure the cluster for System V shared
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* memory instead.
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*/
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staticchar*
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choose_dsm_implementation(void)
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{
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#ifdefHAVE_SHM_OPEN
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intntries=10;
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while (ntries>0)
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{
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uint32handle;
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charname[64];
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intfd;
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handle=random();
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snprintf(name,64,"/PostgreSQL.%u",handle);
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if ((fd=shm_open(name,O_CREAT |O_RDWR |O_EXCL,0600))!=-1)
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{
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close(fd);
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shm_unlink(name);
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return"posix";
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}
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if (errno!=EEXIST)
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break;
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--ntries;
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}
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#endif
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#ifdefWIN32
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return"windows";
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#else
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return"sysv";
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#endif
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}
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/*
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* Determine platform-specific config settings
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*
@@ -1157,6 +1206,7 @@ test_config_settings(void)
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SYSTEMQUOTE"\"%s\" --boot -x0 %s "
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"-c max_connections=%d "
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"-c shared_buffers=%d "
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"-c dynamic_shared_memory_type=none "
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"< \"%s\" > \"%s\" 2>&1"SYSTEMQUOTE,
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backend_exec,boot_options,
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n_connections,test_buffs,
@@ -1171,6 +1221,11 @@ test_config_settings(void)
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printf("%dMB\n", (n_buffers* (BLCKSZ /1024)) /1024);
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else
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printf("%dkB\n",n_buffers* (BLCKSZ /1024));
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printf(_("selecting dynamic shared memory implementation ... "));
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fflush(stdout);
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dynamic_shared_memory_type=choose_dsm_implementation();
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printf("%s\n",dynamic_shared_memory_type);
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}
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/*
@@ -1265,6 +1320,11 @@ setup_config(void)
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conflines=replace_token(conflines,"#log_timezone = 'GMT'",repltok);
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}
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snprintf(repltok,sizeof(repltok),"dynamic_shared_memory_type = %s",
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dynamic_shared_memory_type);
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conflines=replace_token(conflines,"#dynamic_shared_memory_type = posix",
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repltok);
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snprintf(path,sizeof(path),"%s/postgresql.conf",pg_data);
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writefile(path,conflines);

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