greenplumn mainloop 源码
greenplumn mainloop 代码
文件路径：/src/bin/psql/mainloop.c
/*
* psql - the PostgreSQL interactive terminal
*
* Copyright (c) 2000-2019, PostgreSQL Global Development Group
*
* src/bin/psql/mainloop.c
*/
#include "postgres_fe.h"
#include "mainloop.h"
#include "command.h"
#include "common.h"
#include "input.h"
#include "prompt.h"
#include "settings.h"
#include "common/logging.h"
#include "mb/pg_wchar.h"
/* callback functions for our flex lexer */
const PsqlScanCallbacks psqlscan_callbacks = {
psql_get_variable,
};
/*
* Main processing loop for reading lines of input
* and sending them to the backend.
*
* This loop is re-entrant. May be called by \i command
* which reads input from a file.
*/
int
MainLoop(FILE *source)
{
PsqlScanState scan_state; /* lexer working state */
ConditionalStack cond_stack; /* \if status stack */
volatile PQExpBuffer query_buf; /* buffer for query being accumulated */
volatile PQExpBuffer previous_buf; /* if there isn't anything in the new
* buffer yet, use this one for \e,
* etc. */
PQExpBuffer history_buf; /* earlier lines of a multi-line command, not
* yet saved to readline history */
char *line; /* current line of input */
int added_nl_pos;
bool success;
bool line_saved_in_history;
volatile int successResult = EXIT_SUCCESS;
volatile backslashResult slashCmdStatus = PSQL_CMD_UNKNOWN;
volatile promptStatus_t prompt_status = PROMPT_READY;
volatile int count_eof = 0;
volatile bool die_on_error = false;
FILE *prev_cmd_source;
bool prev_cmd_interactive;
uint64 prev_lineno;
/* Save the prior command source */
prev_cmd_source = pset.cur_cmd_source;
prev_cmd_interactive = pset.cur_cmd_interactive;
prev_lineno = pset.lineno;
/* pset.stmt_lineno does not need to be saved and restored */
/* Establish new source */
pset.cur_cmd_source = source;
pset.cur_cmd_interactive = ((source == stdin) && !pset.notty);
pset.lineno = 0;
pset.stmt_lineno = 1;
/* Create working state */
scan_state = psql_scan_create(&psqlscan_callbacks);
cond_stack = conditional_stack_create();
psql_scan_set_passthrough(scan_state, (void *) cond_stack);
query_buf = createPQExpBuffer();
previous_buf = createPQExpBuffer();
history_buf = createPQExpBuffer();
if (PQExpBufferBroken(query_buf) ||
PQExpBufferBroken(previous_buf) ||
PQExpBufferBroken(history_buf))
{
pg_log_error("out of memory");
exit(EXIT_FAILURE);
}
/* main loop to get queries and execute them */
while (successResult == EXIT_SUCCESS)
{
/*
* Clean up after a previous Control-C
*/
if (cancel_pressed)
{
if (!pset.cur_cmd_interactive)
{
/*
* You get here if you stopped a script with Ctrl-C.
*/
successResult = EXIT_USER;
break;
}
cancel_pressed = false;
}
/*
* Establish longjmp destination for exiting from wait-for-input. We
* must re-do this each time through the loop for safety, since the
* jmpbuf might get changed during command execution.
*/
if (sigsetjmp(sigint_interrupt_jmp, 1) != 0)
{
/* got here with longjmp */
/* reset parsing state */
psql_scan_finish(scan_state);
psql_scan_reset(scan_state);
resetPQExpBuffer(query_buf);
resetPQExpBuffer(history_buf);
count_eof = 0;
slashCmdStatus = PSQL_CMD_UNKNOWN;
prompt_status = PROMPT_READY;
pset.stmt_lineno = 1;
cancel_pressed = false;
if (pset.cur_cmd_interactive)
{
putc('\n', stdout);
/*
* if interactive user is in an \if block, then Ctrl-C will
* exit from the innermost \if.
*/
if (!conditional_stack_empty(cond_stack))
{
pg_log_error("\\if: escaped");
conditional_stack_pop(cond_stack);
}
}
else
{
successResult = EXIT_USER;
break;
}
}
fflush(stdout);
/*
* get another line
*/
if (pset.cur_cmd_interactive)
{
/* May need to reset prompt, eg after \r command */
if (query_buf->len == 0)
prompt_status = PROMPT_READY;
line = gets_interactive(get_prompt(prompt_status, cond_stack),
query_buf);
}
else
{
line = gets_fromFile(source);
if (!line && ferror(source))
successResult = EXIT_FAILURE;
}
/*
* query_buf holds query already accumulated. line is the malloc'd
* new line of input (note it must be freed before looping around!)
*/
/* No more input. Time to quit, or \i done */
if (line == NULL)
{
if (pset.cur_cmd_interactive)
{
/* This tries to mimic bash's IGNOREEOF feature. */
count_eof++;
if (count_eof < pset.ignoreeof)
{
if (!pset.quiet)
printf(_("Use \"\\q\" to leave %s.\n"), pset.progname);
continue;
}
puts(pset.quiet ? "" : "\\q");
}
break;
}
count_eof = 0;
pset.lineno++;
/* ignore UTF-8 Unicode byte-order mark */
if (pset.lineno == 1 && pset.encoding == PG_UTF8 && strncmp(line, "\xef\xbb\xbf", 3) == 0)
memmove(line, line + 3, strlen(line + 3) + 1);
/* Detect attempts to run custom-format dumps as SQL scripts */
if (pset.lineno == 1 && !pset.cur_cmd_interactive &&
strncmp(line, "PGDMP", 5) == 0)
{
free(line);
puts(_("The input is a PostgreSQL custom-format dump.\n"
"Use the pg_restore command-line client to restore this dump to a database.\n"));
fflush(stdout);
successResult = EXIT_FAILURE;
break;
}
/* no further processing of empty lines, unless within a literal */
if (line[0] == '\0' && !psql_scan_in_quote(scan_state))
{
free(line);
continue;
}
/* Recognize "help", "quit", "exit" only in interactive mode */
if (pset.cur_cmd_interactive)
{
char *first_word = line;
char *rest_of_line = NULL;
bool found_help = false;
bool found_exit_or_quit = false;
bool found_q = false;
/* Search for the words we recognize; must be first word */
if (pg_strncasecmp(first_word, "help", 4) == 0)
{
rest_of_line = first_word + 4;
found_help = true;
}
else if (pg_strncasecmp(first_word, "exit", 4) == 0 ||
pg_strncasecmp(first_word, "quit", 4) == 0)
{
rest_of_line = first_word + 4;
found_exit_or_quit = true;
}
else if (strncmp(first_word, "\\q", 2) == 0)
{
rest_of_line = first_word + 2;
found_q = true;
}
/*
* If we found a command word, check whether the rest of the line
* contains only whitespace plus maybe one semicolon. If not,
* ignore the command word after all. These commands are only for
* compatibility with other SQL clients and are not documented.
*/
if (rest_of_line != NULL)
{
/*
* Ignore unless rest of line is whitespace, plus maybe one
* semicolon
*/
while (isspace((unsigned char) *rest_of_line))
++rest_of_line;
if (*rest_of_line == ';')
++rest_of_line;
while (isspace((unsigned char) *rest_of_line))
++rest_of_line;
if (*rest_of_line != '\0')
{
found_help = false;
found_exit_or_quit = false;
}
}
/*
* "help" is only a command when the query buffer is empty, but we
* emit a one-line message even when it isn't to help confused
* users. The text is still added to the query buffer in that
* case.
*/
if (found_help)
{
if (query_buf->len != 0)
#ifndef WIN32
puts(_("Use \\? for help or press control-C to clear the input buffer."));
#else
puts(_("Use \\? for help."));
#endif
else
{
puts(_("You are using psql, the command-line interface to PostgreSQL."));
printf(_("Type: \\copyright for distribution terms\n"
" \\h for help with SQL commands\n"
" \\? for help with psql commands\n"
" \\g or terminate with semicolon to execute query\n"
" \\q to quit\n"));
free(line);
fflush(stdout);
continue;
}
}
/*
* "quit" and "exit" are only commands when the query buffer is
* empty, but we emit a one-line message even when it isn't to
* help confused users. The text is still added to the query
* buffer in that case.
*/
if (found_exit_or_quit)
{
if (query_buf->len != 0)
{
if (prompt_status == PROMPT_READY ||
prompt_status == PROMPT_CONTINUE ||
prompt_status == PROMPT_PAREN)
puts(_("Use \\q to quit."));
else
#ifndef WIN32
puts(_("Use control-D to quit."));
#else
puts(_("Use control-C to quit."));
#endif
}
else
{
/* exit app */
free(line);
fflush(stdout);
successResult = EXIT_SUCCESS;
break;
}
}
/*
* If they typed "\q" in a place where "\q" is not active, supply
* a hint. The text is still added to the query buffer.
*/
if (found_q && query_buf->len != 0 &&
prompt_status != PROMPT_READY &&
prompt_status != PROMPT_CONTINUE &&
prompt_status != PROMPT_PAREN)
#ifndef WIN32
puts(_("Use control-D to quit."));
#else
puts(_("Use control-C to quit."));
#endif
}
/* echo back if flag is set, unless interactive */
if (pset.echo == PSQL_ECHO_ALL && !pset.cur_cmd_interactive)
{
puts(line);
fflush(stdout);
}
/* insert newlines into query buffer between source lines */
if (query_buf->len > 0)
{
appendPQExpBufferChar(query_buf, '\n');
added_nl_pos = query_buf->len;
}
else
added_nl_pos = -1; /* flag we didn't add one */
/* Setting this will not have effect until next line. */
die_on_error = pset.on_error_stop;
/*
* Parse line, looking for command separators.
*/
psql_scan_setup(scan_state, line, strlen(line),
pset.encoding, standard_strings());
success = true;
line_saved_in_history = false;
while (success || !die_on_error)
{
PsqlScanResult scan_result;
promptStatus_t prompt_tmp = prompt_status;
size_t pos_in_query;
char *tmp_line;
pos_in_query = query_buf->len;
scan_result = psql_scan(scan_state, query_buf, &prompt_tmp);
prompt_status = prompt_tmp;
if (PQExpBufferBroken(query_buf))
{
pg_log_error("out of memory");
exit(EXIT_FAILURE);
}
/*
* Increase statement line number counter for each linebreak added
* to the query buffer by the last psql_scan() call. There only
* will be ones to add when navigating to a statement in
* readline's history containing newlines.
*/
tmp_line = query_buf->data + pos_in_query;
while (*tmp_line != '\0')
{
if (*(tmp_line++) == '\n')
pset.stmt_lineno++;
}
if (scan_result == PSCAN_EOL)
pset.stmt_lineno++;
/*
* Send command if semicolon found, or if end of line and we're in
* single-line mode.
*/
if (scan_result == PSCAN_SEMICOLON ||
(scan_result == PSCAN_EOL && pset.singleline))
{
/*
* Save line in history. We use history_buf to accumulate
* multi-line queries into a single history entry. Note that
* history accumulation works on input lines, so it doesn't
* matter whether the query will be ignored due to \if.
*/
if (pset.cur_cmd_interactive && !line_saved_in_history)
{
pg_append_history(line, history_buf);
pg_send_history(history_buf);
line_saved_in_history = true;
}
/* execute query unless we're in an inactive \if branch */
if (conditional_active(cond_stack))
{
success = SendQuery(query_buf->data);
slashCmdStatus = success ? PSQL_CMD_SEND : PSQL_CMD_ERROR;
pset.stmt_lineno = 1;
/* transfer query to previous_buf by pointer-swapping */
{
PQExpBuffer swap_buf = previous_buf;
previous_buf = query_buf;
query_buf = swap_buf;
}
resetPQExpBuffer(query_buf);
added_nl_pos = -1;
/* we need not do psql_scan_reset() here */
}
else
{
/* if interactive, warn about non-executed query */
if (pset.cur_cmd_interactive)
pg_log_error("query ignored; use \\endif or Ctrl-C to exit current \\if block");
/* fake an OK result for purposes of loop checks */
success = true;
slashCmdStatus = PSQL_CMD_SEND;
pset.stmt_lineno = 1;
/* note that query_buf doesn't change state */
}
}
else if (scan_result == PSCAN_BACKSLASH)
{
/* handle backslash command */
/*
* If we added a newline to query_buf, and nothing else has
* been inserted in query_buf by the lexer, then strip off the
* newline again. This avoids any change to query_buf when a
* line contains only a backslash command. Also, in this
* situation we force out any previous lines as a separate
* history entry; we don't want SQL and backslash commands
* intermixed in history if at all possible.
*/
if (query_buf->len == added_nl_pos)
{
query_buf->data[--query_buf->len] = '\0';
pg_send_history(history_buf);
}
added_nl_pos = -1;
/* save backslash command in history */
if (pset.cur_cmd_interactive && !line_saved_in_history)
{
pg_append_history(line, history_buf);
pg_send_history(history_buf);
line_saved_in_history = true;
}
/* execute backslash command */
slashCmdStatus = HandleSlashCmds(scan_state,
cond_stack,
query_buf,
previous_buf);
success = slashCmdStatus != PSQL_CMD_ERROR;
/*
* Resetting stmt_lineno after a backslash command isn't
* always appropriate, but it's what we've done historically
* and there have been few complaints.
*/
pset.stmt_lineno = 1;
if (slashCmdStatus == PSQL_CMD_SEND)
{
/* should not see this in inactive branch */
Assert(conditional_active(cond_stack));
success = SendQuery(query_buf->data);
/* transfer query to previous_buf by pointer-swapping */
{
PQExpBuffer swap_buf = previous_buf;
previous_buf = query_buf;
query_buf = swap_buf;
}
resetPQExpBuffer(query_buf);
/* flush any paren nesting info after forced send */
psql_scan_reset(scan_state);
}
else if (slashCmdStatus == PSQL_CMD_NEWEDIT)
{
/* should not see this in inactive branch */
Assert(conditional_active(cond_stack));
/* rescan query_buf as new input */
psql_scan_finish(scan_state);
free(line);
line = pg_strdup(query_buf->data);
resetPQExpBuffer(query_buf);
/* reset parsing state since we are rescanning whole line */
psql_scan_reset(scan_state);
psql_scan_setup(scan_state, line, strlen(line),
pset.encoding, standard_strings());
line_saved_in_history = false;
prompt_status = PROMPT_READY;
}
else if (slashCmdStatus == PSQL_CMD_TERMINATE)
break;
}
/* fall out of loop if lexer reached EOL */
if (scan_result == PSCAN_INCOMPLETE ||
scan_result == PSCAN_EOL)
break;
}
/* Add line to pending history if we didn't execute anything yet */
if (pset.cur_cmd_interactive && !line_saved_in_history)
pg_append_history(line, history_buf);
psql_scan_finish(scan_state);
free(line);
if (slashCmdStatus == PSQL_CMD_TERMINATE)
{
successResult = EXIT_SUCCESS;
break;
}
if (!pset.cur_cmd_interactive)
{
if (!success && die_on_error)
successResult = EXIT_USER;
/* Have we lost the db connection? */
else if (!pset.db)
successResult = EXIT_BADCONN;
}
} /* while !endoffile/session */
/*
* If we have a non-semicolon-terminated query at the end of file, we
* process it unless the input source is interactive --- in that case it
* seems better to go ahead and quit. Also skip if this is an error exit.
*/
if (query_buf->len > 0 && !pset.cur_cmd_interactive &&
successResult == EXIT_SUCCESS)
{
/* save query in history */
/* currently unneeded since we don't use this block if interactive */
#ifdef NOT_USED
if (pset.cur_cmd_interactive)
pg_send_history(history_buf);
#endif
/* execute query unless we're in an inactive \if branch */
if (conditional_active(cond_stack))
{
success = SendQuery(query_buf->data);
}
else
{
if (pset.cur_cmd_interactive)
pg_log_error("query ignored; use \\endif or Ctrl-C to exit current \\if block");
success = true;
}
if (!success && die_on_error)
successResult = EXIT_USER;
else if (pset.db == NULL)
successResult = EXIT_BADCONN;
}
/*
* Check for unbalanced \if-\endifs unless user explicitly quit, or the
* script is erroring out
*/
if (slashCmdStatus != PSQL_CMD_TERMINATE &&
successResult != EXIT_USER &&
!conditional_stack_empty(cond_stack))
{
pg_log_error("reached EOF without finding closing \\endif(s)");
if (die_on_error && !pset.cur_cmd_interactive)
successResult = EXIT_USER;
}
/*
* Let's just make real sure the SIGINT handler won't try to use
* sigint_interrupt_jmp after we exit this routine. If there is an outer
* MainLoop instance, it will reset sigint_interrupt_jmp to point to
* itself at the top of its loop, before any further interactive input
* happens.
*/
sigint_interrupt_enabled = false;
destroyPQExpBuffer(query_buf);
destroyPQExpBuffer(previous_buf);
destroyPQExpBuffer(history_buf);
psql_scan_destroy(scan_state);
conditional_stack_destroy(cond_stack);
pset.cur_cmd_source = prev_cmd_source;
pset.cur_cmd_interactive = prev_cmd_interactive;
pset.lineno = prev_lineno;
return successResult;
} /* MainLoop() */
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